MTN ***** device

I am truly not happy with the service I am receiving from MTN. Last year on the 26 October i toke out a contract phone online,which I did receive as expected. I then returned the device to an MTN outlet and requested to cancel the contract. I then received a note showing the phone and sim was returned. The consultant who had help me with taking the contract called to confirm the contract will be cancelled. To my surprise R1030 was then debited from my account in January and February, I called MTN and was told I have token out 3 device, I told the person whom was assist me am only aware of 2phone which I shoul be paying R300.00. I was told that the other phone is suspected ***** and I should submit an affidavit and certfied Id copy which I did on the 27 March. All the required documents I did submit them at an MTN store in Polokwane. The most frustrating part is that these is affecting my credit bureau as it's currently reflecting I have an amount of R3500 due of a device I never used. I am currently handed over to VVM MTN's legal department. No one assisting me. I have lost hope. These thing is affecting my affordability. Someone please assist me I have names of everyone who assisted me from 2017 till to date.