Airtime reversal

On 24 March 2019, I logged onto my fnb internet banking. I did a pre-paid airtime transfer to my cell phone.

the amount should have been R100.00, but by mistake I transferred R1000.00. I phoned ********** 362 to get this reversed. I am told that they cannot reverse this. I want the airtime taken back and my R1000.00 returnded to me. I do not need R1000.00 artime, I just want this reversed.

I asked FNB to assist and they tell me it cannot be reversed