A Reply to Inquiry about Discontinued Model sample letter.
The reason that you have been unable to find our [product and model no.] , is because this model has been discontinued. We replaced it with [new model number], which offers the same fine quality that our customers have come to expect, but is [selling point].
I am enclosing a list of the stores in your area where our products can be purchased, and would like to thank you for choosing our product.