Billed unfairly

I am an unhappy customer. I am a very loyal customer been with the MTN for year for them to ***** me over like this. I made a cancellation request via an MTN branch on the 1st September Ref# 1 - *** after my contract expired in July, and I was billed month end and the branch did make me aware that it will take 30days to reflect to the retention department and I should expect to be billed and I understood. On the 16 I received an invoice and MTN is again billing me same amount, I then received a call from MTN asking me reasons for cancellation and I told the lady and inquired about this billing invoice and she told me her duty is to process cancellation and I should call the customer care after 2 days tried calling customer care could go through, so went to the Branch again to inquire I was told to take the matter to Head Office as they also felt that the problem is with MTN not with me. Went to 14th Avenue in Roodeport and I was assisted by another lady she also agreed that fault is on MTN side not with me and since they billed me again for October I must reverse the debit order and pay for my other contract since I have 2 contracts. On the 9th of November I again called MTN trying to resolve this matter and see how can it be fixed another champion said I should send email to the Channel Queries and I did that my ref no- baf42***-4ce3-addd-996fb55fa7c1 and till to date no one has contacted me send an email again to them seeking response. Today MTN had the audacity to suspend my other line which I owe them nothing on and the contract is up to date. I want the matter to be resolved but I will not faulted for incompetence of the retention department. A lady I spoke to today from Retention told me that they had back log and it was queuing whose fault is that then? I want this matter resolved. I am disgusted by the incompetence of some MTN Champions.