Fraud and bad service

i had given my htc desire 816 for repair in service center after all my possible things (15times format,safe mode, updates,etc and all) told by customer care to solve the problem. As per telephonic conversation with customer care they told me my handset is defective it be replaced. after calling 15times a day they told me they will repair and not replace it.And if the problem arise again they will replace when i had gone to collect by cell on 2nd june 2015 it wasn’t repair( camera was still not clear and other problem wasnt solved) despite my mobile was damaged, the body near volume button was broken and back body was damaged as they removed the back guard.Despite complaining them so many times by calling and writing mails they didnt not responded me properly and heights was when they told that damage is not done by them but was already their. and to prove that they made changes in the closed ticket and modified it. and i have both that ticket. though being same number how can they make changes. when i had talked with escalation team they told me they will repair the camera but not sure to change the body which is damaged by them. my question is when they have damged by mobile they are ought to replace and give me new one. why should i keep defective mobile. being in warranty.Please help me and later they told me that if i get new handset it is also possible it may be defective, that means they are trying to tell htc india makes defective mobile.