Whirlpool India — Forcefully sold a product that is not all needed

I bought a Whirlpool washing machine which branded that it can wash the clothes on hard water and it has a technology yo sense hard water and wash. That's the main branding of the specific model that I bought. But the service engineer who came for installation and demo told my house members who were not aware of this hard water technology that this machines warranty cannot be claimed if you don't install a filter for hard water which is 397 tds. And charged 2000 rs for the filter. I was at the office when this happened. This is scam. Why should the brand advertise yhe profuct as it can wash on hard water and later tell the service engineer to install a filter that converts hard water and the service engineer perfectly manipulated my house member to buy the product even though it is not necessary. The online price of the product is around 1000rs only and they charged my house member for 2000 rs and never gave the bill also.