MTN and Summer mobile are making me pay for a devise I do not have!!

I received an offer from an mtn 3rd part Summer mobile on the 21st of January, received the phone via DSV on the 26th of January, It was not what I thought it was and I returned via DSV on the 3rd of February. To date the contract has not been cancelled, I am still being debited for a phone I do not have. I have spent hundreds of rands trying to get in touch with MTN and summer mobile, their excuse is that they have not received confirmation from the wharehouse and have no means of contacting the wharehouse.