HTC — Htc keeping phone for more than 45 days

Address:	New Delhi, Delhi, 110018
Website:	htc

I own a HTC One M9 plus. I contacted the HTC service centre which is in District Center in West Delhi on 21st Nov 2015. They told me that my phone will be returned in 3 to 4 days. Today is 31st Dec 2015. Its been 40 days and I have been calling them everyday and everytime I get the same response as you will get in 2 days. That 2 days never came. This is mental torture happening with me. They dont do anything. Please do something for me.