bad service

MTN is the worst company on this earth. Had a contract for years, they put my contract on hold because i could not pay, after i paid everything in full and every month after that. I am on credit at the moment, They did not want to open my account. now account is open they still recieve their money. But they dont want to upgrade my phone because the account is still at legal. been strugling for 5 months now. I want to cancel contract but they said i cannot cancel. MTN wont see a send of me anymore