Over Charged

In April 2015 I went to the MTN store in Woodmead to process the cancellation on my two contracts (R658 per month) with MTN as they ended their 24 months in April. The person I dealt with assisted me and told me I had to call the retentions department on the 18th of May to process my cancellations because otherwise they will cancel early and remove the airtime/data/sms I received at the end of April. I did that and was told that the lady sent the retentions department a note to call me as they were on strike. (I am yet to receive a call and your strike is not my issue). I was then charged R410 at the end of June. I then went to the Sandton MTN store and asked for one of the consultants to tell me why I am being charged R410, he explained that I am currently on a pre-paid status as per his two systems and that this could be a disconnection fee. I was then charged R410 again at the end of July, where I went to the Sandton store again and asked why I am being charged this and I was told that I should speak to the retentions department about this (I should not need to phone more than once) I was then charged another R155 at the end of August. This is atrocious, being charged R975 more.