MTN Handed me over for the contract number i do not know.

I have been handed over by MTN for a contract i do not know.i have never received a monthly statement for this number.I have one contract which i know with Mtn wich im currently using and its active.Last year 2018 i realised that for 2 or more months money have been debited twice from my bank account by mtn for two different numbers of which one i do not know.i went to my bank to stop the debit order.Now debtors are calling me left and right and sending me sms everyday.i went to mtn and wrote an affidavit but still im being phoned by debtors.it seems nobody is able to help me.PLEASE I want Mtn to clear my name and PAY me the money they took from my bank account for the contract i do not know.