HTC — Poor response from HTC for after sale service

Address:	Hyderabad, Andhra Pradesh, 500003
Website:	HTC

I purchased HTC desire 816 smart phone on 1st Oct 2014. I purchased the phone as my company has tie up with reliance CDMA network.

I got problem with my phone in Sep 2015 and submitted it to HTC service center at Ameerpet, Hyderabad. They told that there is problem with the mother board and it should be replaced.
After 15 days I got my phone back from the service center after repairing without any charge as the phone was under warranty.
In Dec 2015, I again got problem of display in my phone. I went to the above service center and they told that there is a problem with phone display and I need to submit the phone for repair. I submitted my handset for repair on 16 Dec 2015. As the phone was not under warranty, I paid Rs. 350/- on 5 Jan 2016 and got my phone (ref no.[protected] but I came to know that there was a problem in SIM insertion in CDMA SIM slot-1. I told to the service center person. He told that there is problem with SIM tray and I need to resubmit my phone for repair. So, on same day i.e. 5 Jan 2016 I submitted back my phone for SIM repair. They told that within one week I can get back my phone with estimated cost of around Rs 1500/-
As there was no communication from service center till 10 days, I contacted HTC customer care center on 18 Jan 2016. I got the replay that due to hardware shortage at service center there is delay.
On 27 Jan 2016 when I went to service center at Ameerpet, Hyderabad, they told that there is problem of mother board and the cost estimation will be Rs. 9000/- When I argued that at the time of phone submission on 16 Dec 2015 and 5 Jan 2016, when there was no problem of mother board how can it come now? They simply told that you take back your phone and send complaint to HTC company. I took back my phone after paying Rs. 175/- (ref no[protected]. The problem of SIM tray is not solved and I have been told for another problem of mother board.
Thus I submitted my phone for display repair. It remained with service center for more than one month and after that I got my phone with two more problem which were not there at all. This is due to the negligence during phone repairing.
Now company is not ready to take responsibility for the mistake done by their service center. I complained to HTC customer care, given mails to them but they are not ready to accept their mistake.
Within one year of purchase I started getting problems in my phone. My phone was in service center for one and half month. I have to purchase another phone worth of Rs. 10000/- for my office work as my SIM is CDMA.
I do not know what to do now? Why should I pay for the mistake / negligence of service center. Pl help
Thank you
Gaurang Dixit
Hyderabad