Havells India — exhaust fan: ventilair dx-0wt/too much noise after installation

I bought two exhaust fans for my washrooms and the day i install them it is creating lot of noise, which is not expected from havells products. I went to the dealer with this issue which he plainly refuse to exchange it and told us to complaint to the company. I request to kindly attend this issue, rectify it or change this model. I have high hopes from such a reputed organisation... Rgds