API rate Limits

I have been using an API for many months nad this weekend we are getting an error about the rate limit.  We often get these errors but we wait for a monute and it works.  I went to my.myob and looked at the API ClientID and Secret and clicked the usage over last 24 hours and get "Unavilable"  I created a new clientID and secret and I note teh newclientID is now a GUID where the old one was not.  Anyway I can now get usage and on the new api key.  I can login and get the access and refresh tokens for both clientID however when I use the tokens it always responds with 403 rate limite error.