Paid up letter

Good day

I had a phone contract with MTN which I fell behind on and they handed me over to VVM. In November I paid my first installment, in December I paid by debit order then I made the last payment on the 29th of December. I was told to wait for 21working days for my paid up letter but I still have not received it the account still appears as unpaid on Transunion. VVM always says they are waiting for MTN and I can't speak to a call centre agent at their call centre because they keep saying the number I've entered is not an MTN contract.