Phone Repair

I purchased a Micromax Canvas Nitro(A311) on 6-8-2015 for Rs. 7999 from ebay for 1 year warranty. My phone’s software got corrupted as on 11-02-2016. I submitted my phone in the service centre on 12-02-2016. They said to return it in the evening. and thereafter i got a call that my phone cannot be prepared here i.e. in allahabad and therefore it has to sent to Delhi for further repairs.. They asked for 22 days.. and returned my phone on 19 April. and that too not Canvas Nitro but a diffrent phone i.e. Canvas Knight (A350). I received my phone as on 19th April and used it for 18 days and the software again got corrupted and again i had to submit my phone in the company for next 30 days. again i got back this phone i.e. Canvas Knight on 6-6-16. But still the phone is not working correctly. And the screen is also tampered. and also i had 32 gb of internal memory and now it is only 12gb. plz help me