How MTN *****s your money

I am upgraded every month on all 4 my lines that is supposed to go on prepaid. This started in August and I get a new cancellation date every month. They upgrade me before the previous months cancellation. Every time I complain I get put on the line with Retensions who never answer their phone. You are dishonest MTN. And dont ask for an account . I could not get 1 for 6 years. WOW how useless.