This is very concerning and scary to say the least and its very good you aware us of this OP even if the amount you bet is small because who knows how often this have happen or will happen again? I wonder what the reason for this if its just a mistake or maybe someone did bet a extremely high amount and the casino trying to do you guys dirty (who placed bets on black).
Also its very strange that it seems to take so long time to solve, like they don't care or take this seriously, IMO this is something that should get full attention and license should be withdrawal until this issue is solved and they can presented what have actually happen.

Hope this will be solved for you OP and thank you for bringing this up to day light.