Cell C identity theft.

Hi, in Febr 2021 on the 1st my bank account was debited with a amount of R 841.12. On enquiry @ a Cell C branch, I found out that my identity was used in Jhb to take out a cellphone contract. So it was identity theft. At that time I was on holiday in the south coast of KZN. When I returned home in Klerksdorp in North-West, I went to a local Police station and got an Affidavit to confirm that I did not take out a Cell C cellphone contract in Jhb. With all the evidence I obtained @ Cell C branch, I opened a ***** case with Cell C ***** department. I got a case number and later by enquiry @ Cell C, they sent me an email to confirm that the contract was stoped and that the debit order was cancelled, but all in vain, because every month since Febr on the 1st, my bank account are debited with the amount mentioned. I don’t know what to do any more, because every month I went to a Cell C store and every time they tell me that the contract was cancelled. I urgently need your help.