It was their choice to give you a bonus, they can take it away just as easy :/
Next time, check everything is right, and check t&c before you start to wager.
Umm. this depends. If the T+C states money can be removed for a specific reason then sure. But if its their mistake they have to change wagering, not remove the funds. Otherwise thats moderately illegal.
Guess it’s no chance to get anything back after reading T&C.
“justspin.com reserves the right to cancel or withdraw a promotional offer and to change the terms of use of the offer at any time, regardless of the information provided with the bonus offer.”