Unauthorized Contract and Debit Orders

Bad experience with Cell C. I have had 2 debit orders amounting to R199 from Cell C Ref (SP********73) that went off in March 2021. I reversed the debit as they are unauthorized. The problem got worse because they debited about R3600 again in April. I could not reverse the debit using my banking app and had to go to the branch to do it. Cell C is clearly ******** people because, I have never ever entered into any contract with them. So I really don't even understand how they got my details.