Poor services from Cell C Repair Centre &Lakeside

I upgraded my contract with Cell C. On the first day I realised that there was two dead pixels on the screen i.e. red spots where the LED screen is not displaying the correct colour. Lakeside mall booked the device in on Wednesday (3 June 2015) as an OBF. On Monday (8 June 2015) morning I phoned the repair centre to find out what is the status is of the OBF. The repair centre advised me that the phone was sent back to the store because the device is encrypted and they could not get hold of the store to provide them with the code. Nor did anyone try to contact me to find out what is wrong. This is exactly 6 days that I am without my phone and still nothing has been done to resolve the problem. On Monday afternoon I was back at Cell C lakeside mall to book the phone in yet again, this time without any codes. The device was only sent in on the Wednesday on an OBF. The repair centre informed me that the phone was sent back to the store as they found nothing wrong with the phone. I am clueless as I do not know what to do next as no one is willing to help and assist. This is ridiculous and it must please be resolved.