Myntra.com — I am unable to return or exchange a dress I bought and the exchange period is just 7 days

I loved a dress and bought it from Myntra. It was Loose for me, so I thought of exchange and get the Medium size one. But the medium size is unavailable. They are now not accepting either return or exchange. I contacted the help center and they are helpless in this. If it restocks then only they will exchange itseems. If not restocked, they just atleast accept return. This is not fair. Our money matters too. They failed to handle this kind of situation. I need value for my money too. Either exchange with my necessary size or allow return. If not both, then it’s a serious problem.