Bad *********** service

My MTN contract was handed over by MTN to SSDA. Last month I wanted to settle my account & made arrangements to settle the account with the collection company. I was then sent an SMS with a reference number to utilise. After making the payment, I then requested a paid up letter (proof of payments were sent to SSDA) . I have been mailing follow-ups for the paid up letter for the whole month of February 2018. Only to be told by the collection company that MTN could not trace the amount because I have used a wrong reference number. My money is lying somewhere in the MTN account and I can't get through to MTN because my mobile number has been suspended and the collection company can't assist. All they do is to send me lousy SMS to remind me that my account is in arreas. Your MTN acc ref ********** 781 is still outstanding. To avoid further action commencing. Call SSDA Tel: ********** 600 Bal R 5 288,28 pay within 7 days.