Are there different "tiers" of GMs?

[Risvertasashi]

Is there just one? I only know of the one that posts here sometimes...

This is probably less to do with some vertical, formal hierarchy and more akin to a tech support case - the kind that can't be resolved within a phone call. Some GM was assigned to your case and is working it, and while all GMs probably have access to the case notes, that doesn't necessarily mean it's a good idea for them to try to jump into the middle of it. Especially if your case requires coordination with, say, the operations team or similar, and a new person would have to start over on communications/coordination with others involved.

So, just have a little patience, I'm sure you'll get the title.