Getting a contract from MTN was a horrible mistake

Horrible customer service!!!! I had two contracts one expired so I called to cancel the contract but it was not done!!!! now I am been charged ARREARS on a contract that I requested to be canceled on a call at the MTN store. They do not respond to customer emails I can not call customer care because the store will not do a sim swap on a sim with ARREARS. Where do I go for help? I HAVE SENT INBOX MESSAGES WITH NO RESPONSE AND EVERY TIME SOMEONE RESPONDS THEY ARE ASKING FOR MY ID AND THEN DO NOTHING....