Mtn insurance

I bought a cellphone from mtn with insurance, but than the device was faulty and send back I app**** for a new contract I did not know I was still paying for the old device that was canceled stil to this day I am paying for it I can't claim for a phone because the policy was never updated to the new device i told them I am willing to pay the difference in as long as I receive a phone they don't want to refund my money as well