Mtn refused to upgrade me on black friday

I have a contract wit MTN for the past 11 years my contract was due for upgrade in July but I always upgrade on black Friday this black Friday they refused to upgrade me they made so much excuses I made 2000 phone calls to call center I even went to mtn head office but nothing no one at mtn wanted to help we went to different stores but still no help I'm paying almost R2000 a month for my contract they even double debit my account don't know wat to do cos now I can't get my black Friday deal because of mtn