Ireland. I've Been reading a lot today about online casino regulations here and how they want to come down hard on this sort stuff, as does the UKGC.Β
You need to get it out of your head that they have done something wrong, they have acted in accordance with their T&C's and haven't,Β technically, done anything wrong.Β
What has gone wrong is that you have suffered due to a failing in their system that attributed you a bonus for which you were not eligible for. You had no idea, got a nice win, felt very good and then got devastated.
The argument is that it is misleading to credit a bonus which is invalid from the start. There shouldn't be a bonus attributed in the first place. It's not like it would be a difficult thing for WHGΒ to make this impossible to happen again.
Some reparation for the stress caused, anger, shock, sleepless nights, damage to your state of mind.
You need to make them see the situation from your point of view.Β Don't attack them, call them rogue, don't lash out or else they will just dig their heels in and get defensive.
Clear heads prevail.
Keep us updated, It will possibly take a long time. For your own sake don't focus on it too much or else you will drive yourself crazy.