What a pathetic answers from 4grinz.com support. Players should avoid playing to casinos like that which put all the blame to their game provider when an incident happens. It is invalid to say that they are out of this. They run the game on their site and it's part of their responsibility.
To propagate this I think it's better for you to make a topic too on the scam accusation sub forum.
A scam accusation should be the appropriate move here. This should inform the public of what happened to OP. It's really bad to see glitches and errors on a game that went sour when people hit jackpots. It's like offering a candy then when they realize they want it back they take it from your very mouth. This issue destroyed a lot of casinos' reputation.