That quote was the response from Kahnawake - they have closed their investigation on the matter...
I see.
Unfortunately, this is a case of "guilty until proved innocent".
Whatever you were doing, it has been classed as "fraud", and the Kahnawake have agreed.
The only way to take this further is to resort to the law.
One possibilty is to use the "Data protection act" to see, and correct, any data held about you.
Many of the third party companies casinos use are based in the EU, if not the UK.
It is the PROCESSOR that has made this determination, based on data it has received and processed. If based in the EU, serve it with a data disclosure notice (£10) which forces it to give you a copy of all the data held on you. If it is wrong, you can have it corrected. If there are mistakes in data held about you, this can invalidate the determination that you are a fraud. You could then sue the processor for damages over it's use of incorrect data.
As well as this, it would be worth checking your credit files, as mistakes here can be fed into the anti-fraud systems used by the processors.
Your previous issues are telling you that something isn't right somewhere, and you need to find the root cause, rather than relying on getting the problem "sorted" at the level of individual casinos.
I personally can't really see how a group of friends playing, and sharing tactics, is FRAUD. The games are all random, and play is against the house, rather than other players. This means there can be no "collusion" that would have any effect on the OUTCOMES of the bets, nor could money be transferred from one player to another. POKER is a different matter, and friends playing together CAN indeed collude, and defraud other players.
FRAUD requires deception, which would entail you having lied about something to the casino, perhaps using false information, or using a friend's details to play a second account at the same casino.