Contract Ended in August and still been billed

In July 2015 I went into Telkom mobile and placed a 30 days notice for cancelling my contract as my contract was coming to an end in August so I had to give in 30 days notices to have this cancelled once the 24 months was up. <br> A few days later I received a call from Telkom and there was a agent offering me a better deal to stay with Telkom Mobile and I advised him that even though the contract was on my name my husband uses it and that he needed to speak to him which he did and my husband asked him to cancel it as he wanted to move to another network provider and requested his number remains on prepaid as he wanted to give it to my 9 year old son for his tab.<br> I was billed in August as that was normal. We then put the sim card in my sons tab as we was under the impression that this was now on prepaid. In October I looked at my bank statement and saw that I was still been billed for this contract.When we contacted Telkom they kept on advising us that this matter was been escalated and now no was calling us back and my husband was consistently on the phone with them with no joy.its been 4 months now and I am still been debited. I am thinking of taking Legal action.