So, are you a paying customer? This seems very unthoughtful of them. Actually i was considering evaluating them for enterprise use, looks like i will have to postpone the evaluation.
So yeah, just use another enterprise app instead. You don't really have much choice.
I know people are saying stuff like this doesn't matter, but I manage at least 15 domains on GDomains now, and I will probably hesitate a bit before adding another. Can I trust Google Domains to grow as my business does? I can't believe you can't pay for more space..
When you have 10,000 employees, you could probably just get a team to author their own version of gmail.