Microsoft offers an add-on to Premier Support called Premier Mission Critical which includes support for SQL Server:
'After the initial consultation, customers receive a dedicated line for support, available 24 hours a day, seven days a week, with priority access to the most knowledgeable experts. If an incident occurs, Premier Mission Critical provides customers with the fastest problem resolution services available from Microsoft Corp., including a 30-minute response time and an engagement process that begins at an advanced support level.'
'Premier Mission Critical now provides support for the Microsoft .NET Framework, Microsoft BizTalk Server, Microsoft Exchange Server, Microsoft Office SharePoint Server, Microsoft Dynamics CRM, Microsoft System Center, Microsoft SQL Server and Windows Server. Support is currently available worldwide in English.'
'Pricing for Premier Mission Critical will be dependent on the level of engagement with Microsoft and the specific requirements of each customer. Customers wanting more information should contact their Microsoft account representatives.'