Unacceptable for the fact that on why the investigation take so long while they can shorten the issue up if they really want to work this things out. If I am the affected user I will never go back here since that is already a bad experience that I don't like to happen again.
Shuffle is somehow a good casino and maybe they just missed or neglect on this issue that's why it take that long and the issue still occur.
But let see how they handle this situations since especially that for sure lots of people read this issue and want good resolution of this case.
This kind of situation may happen in any casino or sportsbook, I remember there was longer case in Fortunejack when player need to wait almost a half a year and the other one on Chips, someone made a mistake on deposit using wrong chain and the fund was recovered and credited to the account after almost a year IIRC.
I dont want use these 2 other cases as a support to what is done by Shuffle with above user as I know how it feel when I'm on the player's side but what I want to say is that some time a case may take that long time to solve.
Of course I hope Shuffle can solve any issue faster so players wont wait too long, but if the case is engaging 3rd party such as 3rd party game provider or 3rd party sports provider then a casino may also wait for the provider as well which may make a case take long time.