Make My Trip - Jet Airways flight refund not issued

I booked tickets for me and my family to visit my elderly parents in Frankfurt for the */*/****. This ticket was booked almost * months before the flight date, since it was an expensive trip and we had saved towards this for more than a year (MakeMyTrip Customer ETicket : NN*************). Our flights were cancelled and we had to take a loan to rebook our tickets at a much higher price with another airlines. I have written more than * times to the Make my trip costumer care and talked to them on the phone many times. Now they say that the booking does not exist! This is a large amount of money for a low middle class family. Please help me resolve this.