Poor call centre service

I fell behind with loan repayments during covid. Fnb has been relentless with sms and calls to get loans paid up to date. I am now in a position to not only get the accounts up to date, but settle them in full. After aboit 30 calls and numerous requests, it is now 2 weeks that I have been battling to get settlement letters from them. Been told that ot takes 3 days for a letter. Countless follow ups has left me in the dark. When asking for a reference number or persons name they simply hang up the phone.