Well I went to their terms and read regarding the [Promotions and Bonuses] it seems very risky condition, I think you must read it carefully and understand if you did not violate the rules, but as they have said there.
[ 9.5. Rocketpot may amend, reclaim, refuse or cancel any promotion at any time at its own discretion ]
Actually, most casinos and businesses have a similar clause in their terms of service. Many of them even add a clause giving them the right to adjust or replace their terms at any time they want at their own discretion. Probably as a way to avoid lawsuits.
But resorting to this clause and applying it whenever a customer make a big profit and requests a withdrawal is unethical by all means and will definitely damage the companie's reputation.
OP, I suggest moving this topic to the
Scam Accusations board and provide as many evidence as you can.
I think that condition is applicable if the bonus is still in effect. And OP had finished the wagering requirement and marked it as completed thus nothing can be canceled since the bonus is already finished. If they reclaim it they should only take the bonus given to the player which is $1500. And it does not say any winning amount from that bonus, does it?