Billed for a phone I do not posess

I app**** for a MTN upgrade for my son. I decided the deal I was getting was a good one and asked for another contract of the same for my other son. MTN advised this was not a problem. They advised that the upgrade needs to be completed first before they can proceed with the new contract. No problem right... Next thing I know I the new phone gets approved & delivered and the upgrade turned down as I now \have too many contracts"(I have 2 other contracts besides these - personal phone and a data contract) After many phone calls and headaches I decided to return the new phone and sim 2 days later (unopened"