Dear
As our new letterhead indicates， we have recently changed the name of our business from    [old name] to [new name]

There has been no change in management and we will be providing the same products and fine service on which we have built our reputation in the industry.  We would appreciate it if you would bring this announcement to the attention of your accounts payable department and direct them accordingly.

Thank you for being one of our valued customers.  We appreciate your cooperation in this matter.