Talk to them sternly and strictly ask for a refund and nothing else. Tell them all local websites like daraz, pakwheels, autohub send a return shipping label to return the product for free. This is how it is done all over the world. You have already wasted 810rs on them and will not spend even a penny more. If they do not agree then threaten them with legal action and name and shame on social media.
These are crooks with zero morality and this is the only way to deal with them. Make noise and threaten them otherwise forget about any kind of return. If you ship it again with your own pocket you will then have donated them 1620rs. Better give the amount to saylani welfare.
