Unauthorised debit.

I am utterly and totally disgusted by how Telkom has dealt with my query. I have had issues with them failing to debit my account even after I had followed up on numerous occasions to try get them to debit and bring my account to order. Consultants I spoke with said that my query would be escalated. They eventually blocked the services on my phone despite the fact that I was still waiting for feedback to find out why they had not been debiting as agreed. I provided all contact info for them to call me for feed back, nothing! I missed a call from telkom, but I phoned in immediately to get back to them but the two consultants I spoke with could not get hold of the person dealing with my case. I then received an sms notifying me that I had been handed over to a debt collection agency to recover the debt which I was still querying. A few days later I got debited by Telkom to settle my account, then I got debited the same amount by NUDEBT which is the company the handed me over to. I am upset that they got an agency to debit my account without my permission and still Telkom went and debited me too..for the same debt. How can this be legal?? I need my money back and this matter to end.