Important
After reading some of the responses in the forum, I decided that what I have done is not the right thing and hence called Flyi last afternoon. Today a very pleasant customer service rep called me back and told me that Flyi has already gathered all this information and it was aware of the glitch and how many more people had used the coupon codes. He offered me a chance to go ahead and pay the extra fare else cancel my reservations. I decided that I would cancel my reservations as I would just drive down to from IAD. What I learnt frm them was that Independence Air can and does police its discount coupon usage for compliance with the rules and that anyone who tries to take use these coupons will be refused transportation by Independence Air.
Moreover, I just felt it was inappropriate that I be defrauding 1. Co-passengers and 2. My favourite Airline.
The rep was quite nice and was very happy that I was also cooperating with him. I am letting know everybody who may have taken my advice and used these coupons that I am pretty sure by now Flyi knows about this and your ticket will be cancelled at the last moment. This is sure to leave you stranded and its better you call up beforehand and pay up the extra $20 .... Lastly thanks to Flygirl ...