MTN - Deteriorating Service

When I first joined MTN I was very impressed with their service and advocated for them telling people how great they were. <br> <br> But not so much anymore. <br> <br> I am a contract user and receive R100.00 airtime every month. Over the past few months my airtime has built up to R600.00, when I checked my airtime balance this morning it was only R4.14 to be exact. I have only made a few calls none of them over a minute long, so I don't get how this happened?! MTN please explain!<br> <br> Also, I buy 1G of data in addition to the 300MB that I receive and it usually lasts for over a month but recently it's only been enough for half of the time that it used to last. <br> <br> MTN's service is poor and if they are having trouble building a customer base, with the problems existing customers have its not likely for new people to join your network.