Unfair billing due to MTN's poor Customer Service

On 22/06/15 I give notice to terminate service. 22/06/15 I receive mail as acknowledgment of notice. On 23/07/15 a month later the apology for delay the matter will be forwarded to the relevant department with reference no: ***3. A couple of weeks later I receive phone calls requesting payment, over R500-00 (about 3 months billing) I explain that Notice was given and that I will pay for one months service should my request did not fall within the 30 days notice ambit. The operator inform me that she will forward the information to the relevant department and that they will contact me soon. Needless to say that did not happen just more calls requesting payment. The next moment I find myself to be handed over to MBD inc. I was furious. Making more calls to MTN (holding about 20 min at a time before speaking to someone) speaking to operators. Ask for the Legal department you find yourself with just no one answering the phone. When at long last I did manage to speak to someone I hope to believe is important there,I was just informed that the matter is with MBD inc now. By now I'm handed over to the credit bureau aswell. Feel like catching snacks with my bare hands.