PUMA - Faulty shoes caused leg injury

I ordered a Puma shoes ( Black leader VT running shoes ) from Myntra few months back. I wore it and was not comfortable with it since start but as shoes takes time to fit in your legs I waited for a month to see the results but it was still uncomfortable. I reached out aggressively to Puma via mail and customer care numbers. They replied me to share the receipt so I shared the order details of Myntra but still they did not respond I again mailed then and they asked for receipt. This happened thrice but then I got involved in something else and now after using it for just * months I have got a bone injury on the pelvic muscle. I am not getting a way to teach this guys a lesson for delivering faulty products at such an expensive price. Pls suggest ways orelse I will be moving to court.