Cell c debiting wrong accounts and will not pay back

Hi I have 2 contracts with cell c I opened it last year October 2018 in April 2019 cell c sent me a message my payment never go thru by sms when I called cell c I found out they are deducting from some one else's account for the pass months they told me it was a credited card account total sum paid was R950 its now a month tying to sort my account out with cell c and I have called over 10 times for them to sort out I spoke to the line manager he so help full but he tried and sent his manager the problem with emails and no response for the pass two weeks no one trying to sort out the account I had a call from cell c one of the agents call and wanted force me to change my bank details I said no I asked wat will happen to the money that was paid by the wrong account they had no answer. But wanted me to change my details I need help frm cell c and they wud not I tried there is two reff frm cell c