Breach of contract

I have an existing contract with MTN for the past 5 years, I've always had problems with MTN not loading my data or at times it would be my airtime. <br> However this time its even worse as I have an unlimited contract package with another service provider so I'm generally not using this MTN line as frequent. My free minutes have never been loaded for the past 3 or 4 months. I think they could see that this number is not really being used tried calling & speaking to one of the call centre agents yesterday & today I spoke to a guy by the name of Sibusiso Mlelo with a reference number of ***. The lady I spoke to yesterday said she had requested for my airtime to be loaded but at vain. <br> <br> Such service from MTN is off & very worrying, who runs business like this.