1) I'm not sure applying bonus 'automatically' is fair. But it's on the player to stay aware and proactively contact support with any doubt. OP didn't, so it's partly his fault that he got into a situation where his money is 'stuck'. Every bonus terms I've viewed on NB state 'Bonus can't be removed from account under any circumstances' (and it makes sense to me)
2) Limiting max bet to 0.5 mbtc - wow this is different. He has 80-90% of a monster rollover to complete. How is this fair, how is this acceptable? Why isn't Nitrobetting posting in Bonus T&C that 'we can limit you to $0.05 max wager to make clearing any rollover impossible and effectively steal your funds'?
This is not everything, the rollover amount counts only on the won amount, I made so far about 240mbtc bets but they counted only about 130mbtc.
So probably I would have to place a more than 1btc to withdraw my own money from their service.
Everything around their "bonus" turns into pure scam...