5 months and still no cell phone upgrade recieved!

I was called by cell c HQ to upgrade my phone, they got the order wrong and sent me the wrong phone, after 3-4 months they still had no record of recieving the phone back after THEIR couriers came to pick it up. After multiple calls from myself and my mother- who the contracts name is under- and multiple complaints we managed to fast track the complaint and get the record number of the phone and was told that the handset would be cancelled and we would recieve a message saying so and R304.33 credited to us for it, and then R53.17 credited for over charging on our current contract cell c just gave us without even asking us, im on some new contract we never agreed to or knew existed, with some wierd data plan. This was 2 weeks ago, we recieved the R53.17 credit but no mention of the cancelled headset or R304.33 credit. Its now 6 months after i was due for an upgrade and i still dont have my phone. Cell C branches have even mentioned how often this happens over the phone and how slack their OWN head office is and in future should come into the store! This is pathetic service and EXTORSION! Unacceptable!