MTN DISAPOINTMENT!

I have been trying to resolve my problem with MTN for the last two years and counting without any success. I opted for a sim and router deal 20 gigs anytime and 20 gigs night. to say the least I was placed on the incorrect package instead I received 10 gig day and 10 gig night. I went to the store on two occasions asking them to put me on the correct data plan, the third month I went in spoke to the manager, at the time was OMAR AT THE LIBERTY PROMENADE MALL. I vented and said I want to cancel the contract entirely and don't want to be held liable for any charges as this was not my fault, we had a verbal agreement. I was handed over to the lawyers and my name was registered at the credit bureau. I approached the store to clear my name all in vain. I bought a car recently I managed to barely qualify for a bond and my name is still not cleared, any advice or help I would most certainly appreciate. I was not refunded in anyway either I paid for a service I've never received.