Indirect Letter Refusing a Claim

Scenario- As the Customer Service manager for Santa Ana Windows, you are responsible for determining which claims will be accepted and denied. Recently a claim has come to your desk regarding a custom stained-glass window you had made for one of your best customers. The window was made to the specifications given by the customer, however the specifications were incorrect. The cost to create the window was quite expensive and therefore impossible to refund the customer.
Your company has done business with this customer for ten years and you do have some concern that you may lose this great relationship. Write an indirect letter refusing a claim to Lopez General Contractors, 1234 Main Street, Santa Ana, CA 93944, attention Ricardo Lopez, to inform of your decision. Be sure to follow the guidelines for writing this type of letter.