You can change your username, but you have to do a support request. They'll be happy to change it for you, but there might be a limit to how often you can change it.

EDIT: Ummm... I misread your post and didn't see that you said you've contacted support already. Oops - sorry for a pointless response! I'm not sure why they wouldn't let you change it, though.

Wait, what? Support has changed usernames before, though there have been some issues lately with some usernames containing special characters. When did you ask them whether changing the username is possible?

Odd that they said it's not possible. I changed my username via help from support a while ago.

Hell, there's even aspecific entry in the Support page. Click on Support, then Contact Us, then choose 'Problems with website and user accounts and GOG Galaxy'. Then Continue. On the next page there's a dropdown menu under 'Problem Type'. Choose 'username (nickname) change' and then fill out the rest of the form. Shouldn't be an issue.

Shit, the thread I wanted was removed.

You know, you may want to add context to things like that. Newer users will have NO idea what you mean.

I wonder if there was some miscommunication in the conversation with support. It's not possible for you to change your own username, but support can and have changed people's usernames for them on request. I'd be surprised if they suddenly can't do that anymore.

Everyone please rise.

Good mornin' Mr e.

You really shouldn't use any words associated with bowels, it gets your suckhole bum chum too excited.

He's probably trembling from euphoria right now.