Ask HN: Facebook vanity urls and page usernames seem broken. Any tip what to do?

Today I've been setting up my FB user and FB page.

When setting up the username for my user, by mistake I have typed the brand name, which would result in

www.facebook/my_brand_name

Then I created the FB page for the brand. However, when I was setting username for my FB page, I was unable to set it up, because it was unavailable.

I realised that I mixed up those two and changed my user's username to the correct one, which would result

www.facebook/my_personal_name

and thus releasing the username ``my_brand_name``.

OK, now the bug.

When I returned back to FB page, and tried again to set-up the correct username for FB Page, it was still unavailable.

I checked availability half an hour later, still unavailable.

Any idea what to do?

P.S. I was unable to find any kind of human support.