Ask if you can swap the tickets for some others that were collected from other passengers and have not yet been thrown away. It's worth a shot.

Or call CS and tell your tale. That may work, too.

I had BS yesterday on a 6 am flight. I bought the drinks anyway and threw them away. I did not want the coupons to go to waste.

Last thing. Stick them behind the tray table so someone on the next flight might see them and use them.