No help with faulty device

I upgraded my contract and the new device delivered to me via courier on 4 May 2015. The device is faulty, I contacted the call centre and reported the problem on 6 May 2015, I was told a courier service will be send to collect the device for repairs. On 13 May I called the call centre again only to be told they will remind the courier service to come collect the device. On 25 May I send an e-mail to the call centre via their web site because I have been trying numerous times to call the call centre but after holding on for 15 minutes there is no answer. There is an automatic reply for the e-mail that says I will have a reply within a week but I am still waiting. I still cant get through to a consultant at the call centre. I have been waiting for help for nearly a month, I am stuck with a faulty device that I need but cant use