Very bad service by Micromax

I am facing many problems regarding the services of Micromax. Within 6 month of Micromax canvas knight A350 purchase, battery of my handset was bulged in one night due to handset charging issue. I asked to replace the battery but they denied and charged me for battery and told that there is no defect in charging of handset. After 15-20 days I faced again charging issue, and

submitted my phone on (25-8-15) with Job sheet no.: N041112 / 0815 / 18785367 to Noida service center and given complain to Micromax.
complain no. MMX2209151069200 (date-22.09.15)
complain no. MMX0310151173958 (date-03.10.15)

From the day of submission they are replying same every time that it will take 15-20 days. One of my friends have already faced same issue with same model of handset and received new handset of lower configuration in lieu of defective handset after 3 month of delay and too much conversation.
in same way after more than 10 mails and lot of calls to corporate office and their tool free no, on 05.10.15 MMX tried to provided me Old handset with lower configuration. so I deny the replacement, then they replied we will resolve issue soon. but after that i am still waiting for their response. i am too much frustrated by service of MMX and planning to raise a legal notice to them.