Khosla Electronics - Selling by misinformation

The desired phone was not present at the shop, so the sales-man sold my dad a different smartphone stating that it has the same features as the one required, whereas it does not. The salespeople took advantage of the innocence of a ** years old man, and took him under confidence that what they are selling him is at par with the requirement, which is a lie. And now they don't want to return the phone since it has already been activated.