FNB REFUSING TO REFUND

On Saturday the 12 of June 2021..I went to Sunward park FNB ATM to deposit money (R4600) and the transaction was unsuccessful and the ATM did not give back the money. I received the ATM slip and debit card. The branch was closed but the security officers managed to get one of the staff to assist with lodging complain. Today, I went to the branch to get the feedback and I was told that the bank can only refund me R1000. I don't understand and I want my money. You must fix it and I want my money