Indigo Airlines — no reserved seat given, no refund processed and no response from indigo on the issue raised

I got very bad experience with indigo airlines. Because of my recent leg surgery, i had booked wheelchair and extra legroom seat (1st row for me and 2nd row for family) by paying additional amount. However, during check-in they gave us different number (14a, b, c) and we noticed it after security clearance. We complained so many times and nobody was ready to help. Finally, they asked us to take refund and take the seat in row: 14 only as the seat was now given to somebody else. This is really stupid as we have booked one week in advance with extra money and we are in need because of surgery - but your staff asked us to take refund. You should have asked the person who had taken on that day only (Late booking) and who was very healthy - no health need for such legspace. Staff asked me to request somebody to give me space in 1st row! After paying money and that in advance - am i beggar that i should be running around and requesting people for my rights? I was called that at least i will get refund - but that also never happened. When i complained - again no refund or not even single response on complaint. I need to find way to tackle them legally now.