Micromax — Micromax unite 3

Address:

Mumbai City, Maharashtra, 91

Hello,
I bought micromax unite 3 around a year ago and it worked fine for a month and then the power button got really loose. It still worked fine for another month but after that the power button stopped working. I went to a micromax serivce centre in vashi. They resloved it and made me pay for it even when it was under warrenty. The phone worked fine for another month and then again the same button problem i again went to the service centre in vashi but a different one they told me it was water damage even though im 100% sure there wasnt any. They repaired it and again i had to pay for it even when it was under warrenty. Then it worked fine for half a month and again the same problem. I went to the same service centre again and there was the other guy who told me there hadn't been any water damage at all. I asked him if the phone could be replaced. The woman there said they cannot replace it. So the guy just repaired the power button again. I paid for it again. And now again the same button problem. If this is some kind of defect then it should be replaceable right?