not resolving my problem within time

I had very bad experience with HTC service center. I made a purchase of htc Desire 816 for23300 on 28/5/2014. after using Just 23 days its stops working. on 20/6/2014. when I go to service center for replacement they said replacement is available only within 14 days of purchase. then I submit my phone for repair. on 3/7/2014 I received my phone but my problem was not resolved. camera still not working. service center authority said you must resubmit the device. according to company policy device should be repaired within8 to 10 days. but after 15 days of submiting my device I have still not receive my phone. when I ask to service center they said they don’t have idea when I get my phone n they will inform me when they receive the phone. I am also call customer care,they said due to lack of material you phone is still in the workshop and even they don’t have idea when phone is get repaired… please resolve my problem by replacing my phone as soon as possible… imei no- 352795060094850. mob no. 8090430367