Makemy Trip - Fake Voucher sent By Makemytrip company

I booked a hotel through makemytrip from *nd of November **** to *th of November **** however, due to visa issue I changed the dates by calling them to **th of November to **nd of November ****. They sent me a voucher with the new dates however, when I reached at hotel, they denied the check in by stating that they don't have any request or confirmation from Makemytrip about the date change and they have marked know show for the dates of *nd of November to *th of November booking. I have been calling Makemytrip for last * days and they are saying that they are working on this concern and will call back in ** minutes but never get call. I have made more than **-** calls to them however, no resolution provided.