Bad upgrade experience

I upgraded my contract on 26/06/2018. Cell C did not have stock of the phone I ordered. I received a handset on 30/07/2018. I ordered a gold phone. The handset I ordered and the handset that arrived, was not the same. I returned the space grey phone UNOPENED, I did not even take a peak to check if I liked the phone, even though I knew returning this phone and waiting for my new phone would probably take a month again. Today I phoned Cell C to inquire as to when my new phone would arrive. To my surprise the handset I returned needs to go through assessment as the box was opened. I gave the phone to the couriers with all plastic sealed. This phone was not opened by me! I want to cancel this upgrade and cancel my contract, I will move to a service provider who actually cares for client service. Can someone from head office please call me to arrange for the cancellation. I do not want to persue the upgrade, seeing that I waited over a month for a WRONG HANDSET to be delivered to me and now they still do not have stock of the gold Apple iPhone 64GB and I could be held liable for a handset not in original condition, that is absolutely not my fault!