MTN SA very bad service and arrogance

In 2015 I renew my contract with the iPhone store in four ways mall but the store did not give me the phone because out of stock. So I cancel with them so I can renew with mtn store in rivonia road. Mtn sa did not cancel it for 4 month billed me R669 so I manage to revise 2 month. Mtn Owes me R1338 with me getting a phone and now I cannot get a contract with Mtn SA. Mtn Safe blacklist me of get a contract with them because there have my money. I have lot of reference nw with them since 2015 ,ref ********** 75. Every time when I apply for a contract I got told that my account is with legal and legal don't call from 2015 until nw.