Billing exceeded and error: You exceeded your current quota, please check your plan and billing details

My billing shows negative, I received no warnings, have plenty of credit. Now get “You exceeded your current quota, please check your plan and billing details.” via the api - topped up extra funds over an hour ago and still won’t clear the error and billing still shows negative. This feels like something that should have gone away when I topped up the balance. Have tried a lot of things but still same issue. Any ideas? App is useless in production right now.