fix couponset expiration date format

@@ -106,7 +106,7 @@ public class MyRewardsOfferCollectionViewCell: UICollectionViewCell {
         subtitleLabel.font = UIFont(name: "PingLCG-Regular", size: 14)
         subtitleLabel.textColor = UIColor(rgb: 0x00111B)
         
-        expirationLabel.text = data._expiration_formatted
+        expirationLabel.text = "έως " + data.formattedExpiration(format: "dd-MM")
         expirationLabel.font = UIFont(name: "PingLCG-Regular", size: 13)
         expirationLabel.textColor = UIColor(rgb: 0x00111B)
         

@@ -252,6 +252,26 @@ public class CouponSetItemModel {
         
         return ""
     }
+    
+    /// Format expiration date with custom format
+    /// - Parameter format: DateFormatter format string (e.g., "dd-MM", "dd/MM/yyyy")
+    /// - Returns: Formatted date string or empty string if invalid
+    public func formattedExpiration(format: String) -> String {
+        guard let expiration = self.expiration, !expiration.isEmpty else {
+            return ""
+        }
+        
+        let inputFormatter = DateFormatter()
+        inputFormatter.dateFormat = "yyyy-MM-dd HH:mm"
+        
+        if let date = inputFormatter.date(from: expiration) {
+            let outputFormatter = DateFormatter()
+            outputFormatter.dateFormat = format
+            return outputFormatter.string(from: date)
+        }
+        
+        return ""
+    }
 }
 
 public class RedeemedMerchantDetailsModel: Codable {