Inadequacy and deducting money from my bank account, months after I have closed my account

I contacted Telkom to cancel my month to month data contract 31 May. Zungy Nomalanga e-mailed me the cancellation form which I completed and forward to ********** 5 June. Did not received any confirmation that they received it. I followed up 14 June again, send cancellation form again before I went overseas. On my return I noticed that Telkom billed me for July and August. I send a message to their online chat, the person was very helpful and asked me to forward the e-mails I have send in June. Telkom refunded me in September for July and August. The lady also insured me that my contract has been cancelled. Telkom did not deduct anything in Sept. 31 Oct Telkom deducted money again. I contacted Telkom, Dineo Nkabinde assisted me. She said he will sort it out. She also informed me that on her side it shows that my contract still have not been cancelled. She send me an e-mail to say it has been cancelled. I am still waiting for them to refund me. End of November I received another e-mail where they say they will be deducting money for Nov, after Dineo assured me it was cancelled, I had to phone Telkom again. I spoke to Telkom again yesterday, supervisor was not available, they said he/he will phone me after 17:00 yesterday, I am still waiting for the call. Telkom still owes me money for Oct which they *******ly deducted out of my account. Do I open a police investigation or do I open ***** case?