eDreams Charged Me For The Failed Transaction

Hi, I booked a flight on December 8 via eDreams. I input a debit card, but the transaction did not push through, and eDreams requested another card. So, I input a new card, which is a credit card, and the transaction was confirmed. I received a statement from the first card stating that you charged me for the first transaction even though the transaction did not push through. I filed a dispute with my bank, but they rejected it, stating that you have already collected the money and they can't retrieve it. I have contacted your customer service via the eDreams app, but all customer service agents are telling me they did not collect the amount, even though I have provided them with the transaction reference that appeared on the bank statement. I am now at a loss on how I can get my money back.