I have booked a flight from Detroit to Riyadh and paid extra fees to make changes but what happened was when I wanted to make changes they asked me to pay 838 dollars to delay it from 14 to the 25th. They don't care about customer services and they don't have special prices anymore. They used to have good deals back in 2013 but now nothing special but their bad services.
Faisal, as a travel agency we do not control airline prices. Very sorry that the fare difference and the airline penalty is an inconvenience. But our terms and conditions do explain when you make changes, be prepared to pay the airline change fee and the fare difference for the new dates. With the last minute change many of the lower fares have been sold out, perhaps being more flexible in the date could of saved you money on the airfare.