What is it about the (hyphenated) word "non-refundable" that is unclear.
You wanna play the game, you should play by the rules.
As one of the posters said earlier. the simple solution is not to book prepaid rates. This is one of the reasons I never do it, even when the prepaid rate is really tempting, which I suspect may have been the case with you.
Caveat Emptor.
Newman