Interesting. So, both mediators rejected your complaint for the same reason (they could not evaluate the case properly)? I don't remember if I have heard something like this before, but thanks for the info. I don't know if any other reliable mediator services may help you since both top-level mediators failed. Seems like you have only one option, which is reaching the relevant Gambling Authority. I would even spend money for such a large amount of money. It isn't very pleasant to see such big wins confiscated by a popular casino. They are kind of popular on the internet, but not for scamming people.