*****, ******* deduction off my cheque account

For the last 3 months Cell C has been *******ly debiting my cheque account. I DO NOT have a contract or account of any nature with Cell C. I reported the ***** to Cell C. They said they are investigating and will contact me, this is after I had to give them an affidavit to investigate the *****. And guess what?? Another amount has just AGAIN been deducted off my cheque account !!!!