This is a known bug.

This usually happens if you're 1 match away from levelling up, but the opponent in that match quits, then after wining the next match, and levelling up, you don't get your reward.

Actually, I can't remember, but you might actually still get the credits, even though the message say you get none.

And while the developers do know about this bug, the bugs that break the game take priority.
As for getting your tokens back? you can wait for a modmin to see your post, and pass the message on to a developer, but who knows how long that'll take.

I'd say just forget about it, and just get those tokens yourself by winning a few matches.