MTN does not care about their clients

A query about the "disappearance" of my minutes and airtime has taken close to 1 month and still counting to resolve with I don't know how many calls from me to MTN. They took away my free minutes on the day that they topped me up with my monthly supply because they said they had rolled over for 60 day. Yet the reason the minutes had accumulated is because they charge me from my airtime for calls that I make. So in essence they double bill their clients for calls- they deduct from the airtime at the time of making the calls then take away the accumulated minutes thereafter stating that they cannot roll over anymore. I requested that they either credit my minutes or my airtime because they cannnot charge me both/twice for calls. It is almost time for the next renewal of minutes and the matter has yet to be resolved. They promise to get back to me with feedback do not even have the decency to contacqt me with feedback, but they never do. I am the one that has to continuously phone back. They sent me an SMS informing me that my query had been resolved probably hoping that I would not check but when I checked I had not been credited for anything. Again, I called the customer service and the feedback I got was that I should call again on Monday because the billing department does not operate on the weekends and there is no indication on the system as to how the matter has been resolved. MTN is a useless service provider that cares nothing about the very people they make their money from. I am so annoyed and disappointed to say the least.