Yatra.com - Charged for Economy Flexi ticket but issued economy value

I had booked my Ticket from Ranchi to London via New Delhi from Yatra.com. The ticket was for Vistara Airways. I booked the ticket in Economy Flexi class as I wanted flexible dates and the luggage allowance in economy flexi is *pcs of **kgs each. After my ticket is booked I get to know from vistara that my ticked is in economy value and not in economy flexi. Due to this I am loosing out on my option to change the flight date free of charge, also my luggage allowance has been reduced to * pcs of **kgs each. Regarding this I have tried contacting Yatra.com through mail and Twitter but they just don't seem to reply and care to correct the booking. This is a clear case of cheating and fraud by Yatra.com. They charge me for Economy flexi which is much more expensive than economy value. And after cheating they just don't care to help the customer.