HTC 816 — Can;t switch on the phone

I purchased HTC 816 from in November 2014 and I had a problem with the phone in February. As it was under warranty period I took it to Haddad Service Centre, Dammam. They said they will fix it within 10-14 days. It has been more than 1.5 Months and I din't receive my mobile back. When ever I call them I don't get proper response. I would like to get this issue sorted out immediately or get my money back or get the phone replaced.