Mtn incorrectly charging me for months

In May this year I noticed that my debit order for Mtn had increased. Upon calling the helpline I was advised that Mtn were charging me for a recurring 75mb data bundle, which I hadnt ever asked for and wasn't even recieving. I was given a case number REQ*** abd told to expect a call in 48 hours and that I would be getting a refund for all the months they had charged me for the extra data. Well no call came, and in the meantime my debit orders have fluctuated. I subsequently called on 20th November 2015 and tolde to expect a call on the 23/11/2015. I am still waiting. I signed up for a topup 100. Which is a straight R100 airtime and 100MBs data. I would love to know how is it that some months I am being debited R185 one month and R191 the next. I feel like I'm being ******. Please can I get a response on my Case number and a refund.