diff --git a/src/components/icons/index.tsx b/src/components/icons/index.tsx
index f65513b..3464619 100644
--- a/src/components/icons/index.tsx
+++ b/src/components/icons/index.tsx
@@ -33,18 +33,6 @@ export const BackIcon = ({ className }: IconProps) => (
   </svg>
 );
 
-export const ArrowLeftIcon = ({ className }: IconProps) => (
-  <svg
-    className={cn('h-5 w-5', className)}
-    fill="none"
-    viewBox="0 0 24 24"
-    stroke="currentColor"
-    strokeWidth={2}
-  >
-    <path strokeLinecap="round" strokeLinejoin="round" d="M10.5 19.5L3 12m0 0l7.5-7.5M3 12h18" />
-  </svg>
-);
-
 export const ChevronRightIcon = ({ className }: IconProps) => (
   <svg
     className={cn('h-5 w-5', className)}
diff --git a/src/locales/en.json b/src/locales/en.json
index 4724e0b..e68e375 100644
--- a/src/locales/en.json
+++ b/src/locales/en.json
@@ -686,7 +686,8 @@
       "noCards": "Card will be saved automatically on next top-up",
       "pageTitle": "Saved Cards",
       "backToBalance": "Back",
-      "empty": "No saved cards. A card will be saved automatically on your next top-up."
+      "empty": "No saved cards. A card will be saved automatically on your next top-up.",
+      "loadError": "Failed to load saved cards. Please try again later."
     },
     "paymentReady": "Payment link is ready",
     "clickToOpenPayment": "Click the button below to open the payment page in a new tab",
@@ -2759,7 +2760,8 @@
           "trafficAdded": "Traffic package added",
           "expired": "expired",
           "daysLeft": "d left",
-          "deviceLimitUpdated": "Device limit updated"
+          "deviceLimitUpdated": "Device limit updated",
+          "invalidDays": "Please enter a valid number of days (greater than 0)"
         },
         "balance": {
           "current": "Current balance",
diff --git a/src/locales/fa.json b/src/locales/fa.json
index 6adf80a..b292fba 100644
--- a/src/locales/fa.json
+++ b/src/locales/fa.json
@@ -550,7 +550,8 @@
       "noCards": "کارت به طور خودکار در شارژ بعدی ذخیره می‌شود",
       "pageTitle": "کارت‌های ذخیره شده",
       "backToBalance": "بازگشت",
-      "empty": "کارتی ذخیره نشده است. کارت به طور خودکار در شارژ بعدی ذخیره می‌شود."
+      "empty": "کارتی ذخیره نشده است. کارت به طور خودکار در شارژ بعدی ذخیره می‌شود.",
+      "loadError": "خطا در بارگذاری کارت‌ها. لطفاً بعداً دوباره امتحان کنید."
     },
     "paymentSuccess": {
       "title": "پرداخت موفق",
@@ -2393,7 +2394,8 @@
           "trafficAdded": "بسته ترافیک اضافه شد",
           "expired": "منقضی شده",
           "daysLeft": "روز باقیمانده",
-          "deviceLimitUpdated": "محدودیت دستگاه به‌روز شد"
+          "deviceLimitUpdated": "محدودیت دستگاه به‌روز شد",
+          "invalidDays": "لطفاً تعداد روز معتبر وارد کنید (بیشتر از ۰)"
         },
         "balance": {
           "current": "موجودی فعلی",
diff --git a/src/locales/ru.json b/src/locales/ru.json
index 7f5b117..efa1516 100644
--- a/src/locales/ru.json
+++ b/src/locales/ru.json
@@ -714,7 +714,8 @@
       "noCards": "Карта будет сохранена автоматически при следующем пополнении",
       "pageTitle": "Сохранённые карты",
       "backToBalance": "Назад",
-      "empty": "Нет привязанных карт. Карта будет сохранена автоматически при следующем пополнении."
+      "empty": "Нет привязанных карт. Карта будет сохранена автоматически при следующем пополнении.",
+      "loadError": "Не удалось загрузить сохранённые карты. Попробуйте позже."
     },
     "paymentReady": "Ссылка на оплату готова",
     "clickToOpenPayment": "Нажмите кнопку ниже, чтобы открыть страницу оплаты в новой вкладке",
@@ -3280,7 +3281,8 @@
           "trafficAdded": "Пакет трафика добавлен",
           "expired": "истёк",
           "daysLeft": "дн. осталось",
-          "deviceLimitUpdated": "Лимит устройств обновлён"
+          "deviceLimitUpdated": "Лимит устройств обновлён",
+          "invalidDays": "Введите корректное количество дней (больше 0)"
         },
         "balance": {
           "current": "Текущий баланс",
diff --git a/src/locales/zh.json b/src/locales/zh.json
index 9e8ddc7..d5b4e1b 100644
--- a/src/locales/zh.json
+++ b/src/locales/zh.json
@@ -550,7 +550,8 @@
       "noCards": "银行卡将在下次充值时自动保存",
       "pageTitle": "已保存的银行卡",
       "backToBalance": "返回",
-      "empty": "暂无已保存的银行卡。银行卡将在下次充值时自动保存。"
+      "empty": "暂无已保存的银行卡。银行卡将在下次充值时自动保存。",
+      "loadError": "加载银行卡失败，请稍后重试。"
     },
     "paymentSuccess": {
       "title": "支付成功",
@@ -2392,7 +2393,8 @@
           "trafficAdded": "流量包已添加",
           "expired": "已过期",
           "daysLeft": "天剩余",
-          "deviceLimitUpdated": "设备限制已更新"
+          "deviceLimitUpdated": "设备限制已更新",
+          "invalidDays": "请输入有效天数（大于0）"
         },
         "balance": {
           "current": "当前余额",
diff --git a/src/pages/AdminUserDetail.tsx b/src/pages/AdminUserDetail.tsx
index 8f8b063..7bf378d 100644
--- a/src/pages/AdminUserDetail.tsx
+++ b/src/pages/AdminUserDetail.tsx
@@ -431,7 +431,10 @@ export default function AdminUserDetail() {
   const handleUpdateSubscription = async (overrideAction?: string) => {
     if (!userId) return;
     const action = overrideAction || subAction;
-    if ((action === 'extend' || action === 'shorten') && toNumber(subDays, 0) <= 0) return;
+    if ((action === 'extend' || action === 'shorten') && toNumber(subDays, 0) <= 0) {
+      notify.error(t('admin.users.detail.subscription.invalidDays'));
+      return;
+    }
     setActionLoading(true);
     try {
       const data: UpdateSubscriptionRequest = {
diff --git a/src/pages/SavedCards.tsx b/src/pages/SavedCards.tsx
index eb73d3a..ef8e5b0 100644
--- a/src/pages/SavedCards.tsx
+++ b/src/pages/SavedCards.tsx
@@ -10,7 +10,7 @@ import { useDestructiveConfirm } from '../platform/hooks/useNativeDialog';
 
 import { Card } from '@/components/data-display/Card';
 import { Button } from '@/components/primitives/Button';
-import { ArrowLeftIcon } from '@/components/icons';
+import { BackIcon } from '@/components/icons';
 import { staggerContainer, staggerItem } from '@/components/motion/transitions';
 
 function formatCardDate(dateStr: string): string {
@@ -30,7 +30,11 @@ export default function SavedCards() {
   const { showToast } = useToast();
   const confirmDelete = useDestructiveConfirm();
 
-  const { data: savedCardsData, isLoading } = useQuery({
+  const {
+    data: savedCardsData,
+    isLoading,
+    isError,
+  } = useQuery({
     queryKey: ['saved-cards'],
     queryFn: balanceApi.getSavedCards,
   });
@@ -55,7 +59,8 @@ export default function SavedCards() {
         message: '',
         duration: 3000,
       });
-    } catch {
+    } catch (error) {
+      console.error('Failed to unlink card:', error);
       showToast({
         type: 'error',
         title: t('balance.savedCards.unlinkError'),
@@ -80,7 +85,7 @@ export default function SavedCards() {
           onClick={() => navigate('/balance')}
           className="flex h-10 w-10 items-center justify-center rounded-linear border border-dark-700/30 bg-dark-800/50 text-dark-300 transition-colors hover:bg-dark-700/50 hover:text-dark-100"
         >
-          <ArrowLeftIcon className="h-5 w-5" />
+          <BackIcon className="h-5 w-5" />
         </button>
         <h1 className="text-2xl font-bold text-dark-50 sm:text-3xl">
           {t('balance.savedCards.pageTitle')}
@@ -112,8 +117,19 @@ export default function SavedCards() {
         </motion.div>
       )}
 
+      {/* Error state */}
+      {isError && (
+        <motion.div variants={staggerItem}>
+          <Card>
+            <div className="py-12 text-center">
+              <div className="text-error-400">{t('balance.savedCards.loadError')}</div>
+            </div>
+          </Card>
+        </motion.div>
+      )}
+
       {/* Cards List */}
-      {!isLoading && savedCards && savedCards.length > 0 ? (
+      {!isLoading && !isError && savedCards && savedCards.length > 0 ? (
         <motion.div variants={staggerItem}>
           <Card>
             <div className="space-y-3">
@@ -150,7 +166,7 @@ export default function SavedCards() {
             </div>
           </Card>
         </motion.div>
-      ) : !isLoading && savedCards ? (
+      ) : !isLoading && !isError && savedCards ? (
         /* Empty state - only show when data loaded and empty */
         <motion.div variants={staggerItem}>
           <Card>