I think someone already posted a good advise, make some noise on their official twitter account and see what will be the reaction of their CEO.
If this is true then it involves a huge amount of money to begin with so the OP has every right to get it back from Kraken. So try that route, create a twitter account and tweet about your case, maybe someone from them will take notice of it because they have a lot of followers and everyone is going to see it, thus their reputation is on the line.
Who knows, this may work and it is free, but I guess that his little voice won't be heard inside Twitter's noise, unless he spams, which I would not recommend.
As already said, I would stick to the original thread and, if you don't get the satisfactory answer you are looking for, try different ways (paid professional legal advice, for example: you already said it is very expensive but it might be better than losing 50k). This forum is a great source of knowledge but, unfortunately, panacea doesn't really exist. I'm sorry about not giving you an advice that solves your problem directly, but I don't know well the legislation that corresponds to your jurisdiction and, in addition, this is not an easy task and would need a lot more information and time.