Service Notification

I received a Service Notification from Norton regarding my "Virus Removal Assurance".  The notification stated I could either apply a credit to a future Norton product purchase or request a cash refund.  When I opted for a cash refund, the steps requested that I give my full banking information (acct. no., bank name, routing number, etc.).  I am hesitant to fill in this information.  I would rather have a credit applied to my credit card used to purchase the original Norton product.  Is this notification real or a scam?