MakeMyTrip India - Refund not processed despite of VISA refusal

I booked an Lufthansa international flight ticket through MakeMyTrip from Delhi to Berlin on **nd December ****, but was unable to travel because my Schengen Visa application was rejected by the Germany embassy. When I contacted MakeMyTrip and sent them the visa refusal letter days before of my travel date, they state that the refusal copy is not stamped by the German embassy therefore will be unable to process the refund as Lufthansa is not accepting the letter.

When I contacted Lufthansa, for I also booked the additional seat reservations through their website, they state that the seat reservation refund will be processed once MakeMyTrip cancels the flight tickets and processes the refund + cancellation.

I sent the same visa refusal copies that I received from the Germany Consulate in Chennai, When I contact them they say that the letter from embassy has its monogram and bar-code scanner along with the transaction number and date. As per the airline and Lufthansa policy, I am entitled with full (***%) refund on both my flight and seating tickets.
Below are the details of my ticket details. attached are the copies of my visa refusal letter along with passport.

Kindly please help

Lufthansa Booking Code : UDV*MG
Ticket number : ***-**********

Thanks,
Krishna Kartik Tiruvuri
**********