Check which of their services are enabled in apps for domains. Enable anything you believe to be relevant to what causes the errors.

Working for other users of the domain (including myself).

Their support people keep saying vague things about something being wrong with the account, or it being blocked, or the security being not right. But seem to be incapable of fixing it.

The irony ... http://googlesupport.com

> Google Support is unbelievably awful - anyone got any sugggestions?

Don't use Google.

How hard do you work for non-paying customers?

He's trying to buy things on their store, using a phone he bought from them.

That sounds like a paying customer to me...

I've been a paying customer of Google Apps before, the support doesn't improve much.

I have to second this, I had an unpleasant experience with them when trying to sort out a geolocation issue, their support team had no idea how to correct the issue & it took their developers a week to figure out how to fix it (apparently), it was a further week after the issue was resolved that I got a follow-up message from them telling me that it should be fixed.

And when I indicated my dissatisfaction with the experience I got 2 e-mails (and, when I declined in those, a phone call) asking me to change my "moderately satisfied" rating of the experience because Google doesn't consider "moderately satisfied" to be on the "satisfied" end of the spectrum.

It sounded like their support people weren't given the right tools to do their jobs & get harshly auto-performance-rated based on satisfaction surveys.