MTN Upgrade fails

Where to start. Been trying 3 weeks to upgrade my contract with MTN. Countless calls, emails, even tried through Twitter. Calls dropped, pushed around to dept after delt. Spending an hour a day getting frustrated. Call centre reception is terrible. Calls are noisy and eventually dropped and you start all over again. Asked to speak to managers, who are said to be busy and will call back. Never heard from them. Emailed senior people , no response, so it's no wonder the lower level treat their customers like this. This is my last resort. If I don't get an answer in 48 hours I will cancel all 5 contracts.