"Service temporarily unavailable. Please try again in a few minutes" is not about your account. It has nothing to do with your balance, your membership or your image. It means the generation service behind that page has failed several times in a row and has been paused for five minutes so that further attempts do not pile into something that is already broken.
Wait five minutes and run it again. There is nothing to fix at your end.
Why a pause rather than an error each time
When the service upstream stops responding, letting everybody keep submitting makes it worse and gives every one of those people a failure. So after a run of failures the page stops accepting new work for 300 seconds, and the first job submitted after that window tests whether it has recovered. If it has, everything goes back to normal at once.
The pause is not per account. It is the same pause for everyone using that page, which is why it can appear on your first attempt of the day.
The three pages pause separately
Render and Stage share one. Upscale has its own. Edit has its own. They fail independently, so if Render is paused, an upscale or a masked edit will usually still run. That is worth trying before you wait.
Your credits are not returned
This is the part to be careful about. Credits are taken when you press Generate, before the job runs. A job that then fails, including one that fails because of this pause, does not get them back automatically.
So do not sit there pressing Generate through a pause. Each press is a new job, each one is charged, and each one fails the same way. Wait the five minutes.
If you have lost credits to a failed job, contact support with the job from your Jobs page and ask for them back.
Jobs that failed for other reasons
Before it gives up, each job retries twice on its own if the failure looks temporary. So a job that reaches Failed has already been attempted three times, and running the same thing again immediately is unlikely to behave differently unless something has changed at the other end.
A failure that names something about your image, rather than the service, is a different matter: see what you can upload.
The free route while you wait
Asking the assistant in chat to generate the image draws on your free daily allowance of five images rather than your credits. It uses the same service, so it is not a way around the pause, but it is the cheaper place to retry once the pause lifts. See renders in chat are free each day, the tool pages are not.