HTC — not repairing phone

Address:

Visakhapatnam, Andhra Pradesh

hello, i am using htc one x+ phone...i have given it to repair with complaint of screen blinking. I have given twice in 20 days time but the problem is not resolved and now got a new problem.the problem is if i am pressing the lock button once, it is getting switched off immediately. when i call to customer care and complain, they ask me to send it again for repair.but they are not succeded in their work.i am not satisfied with them.tomorrow my waranty is going to end, and if no waranty they will charge me huge amount if i give for repair.i have asked them to replace if they cannot repair, but they are not doing that.so, i request you to help me with my issue. thank you