Myntra.com — myntra account hacked - myntra credits worth 7000 used

I had 8000 myntra credits in my account. Someone hacked my myntra account and ordered speakers worth rs.7000 using my myntra credits. I am surprised to see the lack of security features in myntra as the hacker was so easily able to hack into my account without me getting any notification on my email id / mobile no. Upon calling myntra, the customer care rep very casually asked me to change the password and took no further step.

Date of incident - 3rd may 2019
Mobile number of the hacker - +[protected]