Flipkart - Flight booking with Flipkart

I have flight booked with Flipkart for **th Jan Vistara , for some reason I wanted to reschedule for **th Jan. The only option to reschedule is to submit request online.
I submitted request on *th Jan which they called me on *th Jan. In the meantime i keep on calling their customer care and they were asking me to wait. In the night they sent me the details that they have got approval from airline and it would take **** rs to reschedule which i replied as “YES” within ** mins. ( it was *:** pm , *th Jan).
I called them multiple times , there was no call no email to send me the payment link. On ** Jan *:** pm ( ** hrs after sending an email)
They said that flight is full and you need to provide another flight details to reschedule. Another flight after an hour has increased its cost to *k pp. We are too people so now I need to pay **** + **k for *:** flight which i even dont want.
Tweeting , sending email all are into vain and they are not reply . I have list of full communication which I can send on request.
Its a trauma for me.Please help