FNB poor communication

REF:***. 11August 2020 I received a large amount of money into my FNB Credit Card with a strange reference number. I spoke to 3 different people at FNB Call centre who could not trace where the money had come from. I emailed the FNB Card division to enquire about the money. Next day it was removed. I still need to know where this money came from and why it was deposited into my Credit card in the first place. To Date no communciation from FNB.