FNB alleged personal lian

In the lockdown April last year I talked to a consultant from FNB on the phone about their release loan. I had difficulty to pay my Westbank credit card installment. He send me an email with paperwork I had to complete and sign as well as documentation that I need to send back with the application. Before I could do or send back the paperwork my property was sold and I was able to pay the full outstanding amount on the credit card. June 2020. Now a year later I constantly get conputer phonecalls from FNB because my personal is in arrears. I phoned them requesting details on the signed application etc. They do not reply. I then went to the Riverside branch in Nelspruit and they made me call the loan department again. I made the same request. Up till today they did not send me any signed application or even a account number for this loan. After that I spoke to a consultant again, making the same request. They did pay 2 amount into my credit card and I am willing to pay them back but with no intrest. Firstly how on earth do the approve a loan without the proper signed documentation. Secondly they did not send me any email regarding an account number or even a statement for this aledged loan. Now they haraz me with constant computer cals telling me I am in arrears. My credit score is badly influenced by this and they do not bother to sort the problem out. I have no idea how to resolve this. Please help me