HTC — Booting problem since couple of months of buying

Address:	753012
Website:	www.htc.com/in

I have bought a HTC Desire 616 Dual SIM in the month of August 2014 The problem with the set started 2-3 months later.The major one being "Stuck in booting screen" for which i have visited their service centre thrice during warranty period. Every time they did a complete formatting & it works fine till again the next occurrence of same problem. This time when happened, the service centre informed me that it cant be no longer be formatted hence the motherboard needs to be changed which is costing Rs6000/- (I have to pay since no warranty) My complain is that when i have visited their service centre thrice with same problem 1) why they had not changed the mother board at first or second instance 2) when the set repeatedly stuck with same problem why it is not considered as a faulty part or set & replaced by the company or change mother board to fix the issue permanently. 3) now if i dont pay 6k to repair & my 15k phone will be of no use than to put it into a bag of broken toys of my daughter 4)Complain to service centre-why they have waited the mother board to be changed after the warranty period not during it when the issue had occurred thrice I want a resolution for which i dont need to pay anything for faulty parts which they had shipped in the new phone except other than their service centre fees. Attachment-Mail correspondence from service centre Thanks.