Meeso online shopping app - less quantity deilvered

I have order * nos of Choco brand double size bedsheet. I received only * pc instead of *. once complain they ask to return. The return request done through online and they picked up back the package. However they refunded only Rs. ***. I mail on their given id but no response. Just stated download the app and complain through app. I did so but nothing done so far. This is not the matter of small amount of money but the matter of the services they are providing. I am sure it's not the single case they must doing with other customer as well.