Mtn and their trashiness

I took out a contract with mtn of which was R169. When i received my bill for December it was R890. I then followed up and found out that the contract was **********ly upgraded. They asked that i submit an affidavit stating that the contract was not upgraded by me. I did that early in May. I have never been contacted to give me an update. When I contacted their call centre, they cannot assist me as the account has been handed over! When I contacted the company they handed over to, they cannot find me details! Now when i tried to take out a contract with Vodacom, Boom MTN’s account on my credit record as Handed over! How can they ruin my credit record like that. Mtn can be so TRASHY, I regret even associating myself with this network