"too many requests" to insert billing information

[lilac brook]

I am getting a "too many requests, please slow down" error when I try to insert my billing information for the API. The error is in the UI only when I try to add billing information for the first time. I only made one request with the API, so this error is surprising. Has any body else gotten this error for this reason? How long should I wait before trying again? Waiting a few minutes is apparently insufficient.

[lilac brook]

On an earlier occassion, I used all of my free credits. I wonder if this is some sort of bug having to do with having $0 balance, leaving me in a Catch-22 where I can't add a balance because I don't have a balance.