Ask HN: Getting your company username on social media

I see a lot of popular startups appear who have catchy names/domains of which they obviously bought from a third party with very generic dictionary words or play on words, and subsequently also appear to obtain their original username across these major social platforms of which are nearly impossible to get in actual human contact with -- and I'd like to ask, how?

My company is over 5 years old now and since day 1, our username on Twitter is an account with the real name "Testing 123 123" from 2011 with no followers/follows, and our username on Facebook appears to not be in use yet walls me off when attempting to use it saying "this username is already in use" and email after email, we appear to get botted responses with no light at the end of the tunnel.

Is there any appropriate channel for things like this? Twitter seems to at the very least somewhat be contactable albeit botted responses, but Facebook has no front-facing support for this whatsoever with rather outdated help pages.

At this point, I'd shed tears at the thought of being helped with this by someone in the position to do so.