Shocked

I am an absa premium client with two credit cards, this morning I received a call saying that my credit cards are in total 19k in negative . I have not given absa any consent of letting my accounts go into a negative while I’m under the impression that it still has a positive balance . I also did not get any sms or notifications that my credit cards are in such a huge negative balance as I was under the impression that both are in still positive balances, as I also bank with nedbank and they don’t even allow me to go to a negative 10 rand on my credit cards. I do not mind paying the finance charges for both cards , but the negative balances I refute to be liable for those amounts.