I'm not a woman, but I hope I'm allowed to answer.
Prize-winners very often don't make it to the presentation, either because it happens so long after they've finished, or because they weren't aware they'd won anything. To assume they must be men is a bit of a bizarre concept. Sure, if the organiser wants to award prizes only to the highest placed female who actually waited around, that's up to them, but it's a bit odd. But, as I say, you really can't assume they're men just because they're not at the prize-giving.
But yes, lady-boys winning prizes does happen from time to time (if there's a race photographer, they can be exposed properly - was there one at B-C?), and swapping numbers without going through the organisers is a scummy practice (for plenty of other reasons too). Sorry you've been messed about by a lowlife like that.