What a bad service

Had the bad experience with mtn. I need to cancel my contract but I am not getting assistance. I called the service line to cancel, I was given the cancelation amount to go pay at the store, which I went to pay. They told me after paying I must call again to finalize, I call again I'm told of a different higher amount. Even the customer care agents a re very rude and one hung up on me. I just need to cancel my contract