unauthorized debit order from MTN service provider

I have a contract with MTN for a wifi that they debit account for every month on my pay day. I have recently realized that they are debitting my account Twice every month. I called their call centre on the 9th January 2019 and spoke Princess to enquire about the debit order going through on month end. She advised on my account its showing my debit order that i signed for with my account number A ********** . When i gave her the other account reflecting on my bank statement which is A ********** i was told this is another contract for another customer whom i dont know. The following day i called Tlotlo as the same call centre and he told me the same thing and that i need to send my bank statement, certified id copy and an affidavit. when i requested information of the other contract i was told that that information cannot be given to me but i am paying the contract since July. He tried calling the other persons number to no avail. I have also asked for the proof me taking out that contract and advising my banking details on the second contract either signed document or voice recording. I was told i first need to submit my documents. on other months there wa sno funds in my account MTN went into my account and tried the debit order then my bank charged me an amount of R146 for the unpaid caused by Mtn. When speaking to Tlotlo i asked for a manager or team leader, I was told they are not in the call centre. I then requested to be called by a senior till today I have received no call. I went on the MTN Facebook page where i was asked to send my id number,affidavit and a certified id copy. how do i trust this company that is taking money from my account to pay someone else's contract on facebook. I need MTN to sort this out as this is not my fault and I cannot keep paying for an extra contract that I know nothing about. when i reverse the payment the following month they debit double. I need feedback urgently.