Myntra.com — fake order placed and myntra credits used. no response from myntra

Address: Pune, Maharashtra, 411008

I noticed that someone has used my myntra account and placed an order (ORDER NO:[protected]-8928903) using Rs.2402/- myntra credits in my account.
Basically someone logged into my account, changed my mobile number & address in profile (for which myntra has no OTP security) then placed order using Myntra Credits, while placing order using credits Myntra sent OTP to new number.

When I asked Myntra Customer Care about the same they gave very lame response and told me to change the password. I asked them to provide me the details of how my account was logged into, when they said they are unable to give such information. When asked to take my complaint customer care person said that they are not going to take complaint.