Sorry to hear about the recent issues you have been experiencing.
You will need to make sure you are logging into Studio One using the same information you log into your My.Presonus.com. Troubleshoot, by first logging into My.Presonus.com to ensure you are using the correct credentials.
Once you are in your account, make sure you are in the correct account by verifying you see your registered software. After doing this, go back to Studio One, log in with the correct information. If you run into further issues, please submit a ticket to technical support.
Also, please check out this article which may help: http://support.presonus.com/hc/en-us/articles/210050023-Studio-One-3-Invalid-Login-and-Email-Error-
Should you need to, here is a link to create a ticket: http://support.presonus.com/hc/en-us/requests/new