Hache, you are in luck.
I also made a deposit there, and at least in the No-Download casino software, you can click on the "Cashier" link and then click on "Game Logs" it should have every bet you made listed with the complete details of the hand, dealer cards, who hit, etc etc.
It will take a while to add up by hand, but at least the info is there for you. Once you are sure that you've satisfied the 15x, you can confidently request your payout.