Please reach out to support regarding your account, but I will ping the team to verify that statement credit occur automatically.
There are lots of variables involved with call quality, for sure. It could be carrier coverage, of course, but even software configuration is a factor.
I recently messed things up on my phone, for example, while doing something you’re not supposed to do (creating a Frankendebian - in this case, a byzantium/crimson hybrid with incompatible dependencies, etc. Before resorting to a backup or reflashing my phone, I tried to fix it by reverting various (…well, a lot. over 500) software packages. Call quality was intolerable after these tweaks (others complained about static, dropped audio, etc.) whereas call quality was clear and pristine prior to my goof-ups.
So my point is that you can mess up call quality based on your software configuration (and if you try to do fancy but dangerous things like I did).
These are the rough edges that were alluded to in the outage emails; it’s a known upstream issue and there seems to be nothing Purism (or even the reseller) can do about it. The good news is that it’s only a temporary support issue and does not (and has not yet with any customers so far AFAIK) reappear.
We tried to mitigate this issue in testing but it appeared like a fruitless endeavor and the temporary inconvenience simply was not worth further extending the outage.