Myntra - Wrong Used Shoes delivered by Myntra

I ordered for Skechers shoes on Myntra for Rs **** along with jackets. I received all the products in a big polythene bag of Myntra but when I opened it, the shoes were in cardboard box without any cellotape on the box. The shoes inside the box were in a polythene and were used Puma shoes without any tag on it. I called Myntra and told them about it and also have sent them photos but they rejected its return.
How can it be taken for granted that only customers do the fraud? Is there a way that Myntra should be asked to have a rigorous re check on the items they have packed? I am really very disappointed with this. There packing crew or someone has changed the shoes and I am the bearer of Myntra's wrong doing. I want the return to be done and refund made for the Shoes. Really dishonest and disappointing behaviour from Myntra.
I want to file a complaint against Myntra and sue them for the stress they are giving and not playing fair at all.