...then moved them my blockchain account where they stayed for a couple of years. Then few months ago I decided to move them back to my private wallet.
If your account was inactive during all those years that could be a reason for the 'delay' in pushing your transaction through. This would not justify it, reason why I recommend not using such custodian platforms at all. But you would have to dance with the customer support for the best possible outcome.
A law suit may not give the best result, especially if you are not living where the company is registered in.
- Jay -