QuickBooks Login Credentials are Not Accepted

I’m trying to help my client, Bl**da De**rry sign into her desktop account, so she can then download her 2015 QuickBooks Premier onto a second computer. It is already installed on a laptop……I am coaching her through the sign-in process by telephone, but once she clicks on “QuickBooks Desktop Support” her login credentials are not accepted. Is there a “best” number for her to call to resolve this?