I haven't heard any class suit actions against a dubious and scam exchanges. Although I will say that there are lot of scams of companies claiming to help you out and then will ask you up front payment and then nothing will happen.
And it really depends on your location and the jurisdiction on the exchange themselves. I know there is a
Legal board in this community, perhaps you can ask there as well.
There are already many users that tried to file some lawsuits with online exchanges or gambling platforms (any websites that scammed them) and went successful. I don't know nor really remember when I have read it here in scam accusations but it is really possible and you can win the case as long as you have valid evidences.
With regards to the OP, any lawyers would back you up as long as your claims are true and correct. But still, there are a lot of scammers that are much brighter and could win the case if and only if the evidences are purely alone by one person and without any other supporting claims.