Stuck in an upgrade loop and can't get out, so off to Vodacom!

I have been a contract customer of MTN for 18 years but no longer. I want out. I have been trying to upgrade since March this year. Many MTN operatives have tried to help me. Trouble is in March someone at MTN did 'something' on my account which prevents the average call agent helping me... heck half of them can't even work out why they are unable to help me and, promising the world, just pass my paperwork to file 13. I have decided the only way to proceed is to move to Vodacom - I cannot continue to pay every month for a service I am not getting. I have tried to tell you MTN, tried to make this right in many many phone calls and online queries over the last 4 months but to no good end - so Sayonara MTN