Bajaj Electricals — 3ltr morphy richards geyser

I have recently purchased morphy richards 3 ltr geyser with them i also purchased 3 more gyser of same brand and one same article but in one geyser i got the defected piece and i went to get the product replaced but the shopkeeper declined for the change as they say company person will come and check that and the service agent came and saw it they changed its thermostate and then again i faced the problem then they changed its tank and now it is not working. In a month i have faced 3 problems and their executive is saying that they will not replace the piece they will only repair the geyser.