FNB REFUSING TO REFUND ***** CLAIM

I have been with FNB since my varsity days till to date, Last year I went to FNB atm to withdraw money. The atm allowed me to process my withdrawal till where I needed to select the amount and did not allow me. I tried twice and left the ATM because I could see that it was not allowing me to process my withdrawal. I left and after 10 minutes I received notification that R2500 has been taken out of my account. I went back to the atm and did not see anyone and decided to go to the bank to report the issue. The sales consultant assisted and destroyed my card in my presence and lodge a ***** case. FNB came back after a week and said it was my negligence and they will not be refunding me. What confused me the most, I had my card with me and did not ask anyone to assist me with withdrawing. The atm got stuck and I dont know how that is my negligence. Lastly I had my card with me and did not lose it. The bank refused to refund me while it was their atm that was tempered with by *********.