Swiggy - Item missing in the order only half order received

On Monday (*st May ****) I ordered two boxes (half KG each) of dhokla from Haldiram's via swiggy, but received only one half KG box.

First i tried to contact them on their app but didn't find any number so i chat them but unbaled to do the live chat, i raised the concern they told me that they will contact me in *-* hours, so i called haldiram's they told me that they only received one box order from swiggy and advised me to connect with swiggy, then i called delivery boy he told me he can't do anything.

Then i received an email from swiggy about a coupon of Rs **, i asked them on what basis they are offering me only Rs ** while the total cost of dhokla Rs *** (after discount). But they are saying that this is the best what they can do.

Now my question is if i received half of the order and getting harassed from the last * days then why should i settle for Rs **, what's the logic?