Myholidays.com - Flexible Flight Ticket rebooking issue

I had booked two flight tickets from Sharjah-Kochi for ** Dec **** and return on *th Jan **** via Myholidays.com platform, with an additional payment of *** AED (Rs *,***) for free change of travel dates. On**th November, over a month prior to the travel, I informed them over email that I need to postpone my booking to *rd & **th of June. They replied that they will confirm with the airline and get back to me. But there was no action after that, following which I sent numerous reminder emails.

Finally on the day of travel (ie, **th Dec) I received an email from Myholidays asking for the confirmation of the revised date of travel. But once I confirmed, they responded that the said travel dates are not available. So I asked to rebook for another date instead as I was flexible on travel. To this I received the below reply from Myholidays on ** Feb ****;

" Dear Customer,

We have reviewed your booking and found that your ticket was No-show(not reported at airport) hence changes not permitted.

Sanoj P. S.

Ticketing Executive"

They further replied that the tickets are non-refundable when I requested for refund. This is unacceptable since I had informed them over a month ahead of the travel that my flight tickets need to be postponed to June. But due to the lapse on their side, they are denying the change of travel dates nor refund. I have the booking confirmation, flight ticket and the complete email history with the customer care regarding date change request.

Though MyHolidays had levied charges for flexible travel dates from me, I couldn't find a Flexi-option mentioned anywhere on the flight ticket of GoAir. I doubt if Myholidays had booked a non-flexible ticket with the airline.