Account not closed after settled

Im now getting calls and Sms from a company called MBD INC that my standard bank credit card is seriously overdue and requires urgent settlement. If im not mistaken they said the balance is R1,700.

I find this very strange because standard bank handed over my account to Bham&Dahya (CK97/43837/23) last year (2019). we had made arrangement with these people and gave me a settlement amount which was paid and cleared on April 2019.

I'm not sure why standard bank is now giving these new guys (MBD Inc) my information because the account was settled. I find this strange and **********. how can 1 account get given to 2 different people for collection. I have got all the supporting documents for this.

I want standard bank to resolve this as urgent as possible