Impossible to cancel contracts. Useless service

Impossible to cancel contracts! My contract expired a month ago and I started to call the so called "cancelation department" two months before the contract expired. I have spoken to Nearly ten call center agents and all of them told me that the cancelation have not been lodged yet and that they themselves will do it for me. I have to phone every week to check if it is in fact cancelled and still nothing. I need my contact cancelled asap! We are moving out of South Africa. This service is the worst that I have ever experienced.