No respond i am utterly disguisted with the service

Hi , i am struggling with MTNSP with my contract, ive taken 2 contracts 2 years ago , on both contracts they have over billing me for 4 months , contact them say can't give me a reason ,called numerous times , and then one consultant told me that MTN is billing me incorrectly ,was at the store in kenilworth centre they told me i should contact call center, called the call center they sending me to the store , back and fourth up until today,i have send mtn legal they send me an email with a waiting period after a few days they send me an email stating my case is close , but no help, i refuse to pay the account i am waiting on them to refund my account which is R5k over charged ,i am done with mtn wont advise any of ny people to take out contracts with them.