Your Name and Address Information:
Your Name
Your Address
Your City, State Zip Code
Your Phone Number

Date

Company Information:
Company Name
Company Address
Company City, State Zip Code

Salutation:
Dear Company

On (date), I purchased a (product), a (product description), (product serial number), (product model number), at the (store name and location), for (purchase amount).

This product does not work properly.   It does not (in as much detail as possible, describe the issues with the product).  I am highly disappointed and expect a resolution.

To resolve the problem, I would appreciate an exchange for an equivalent or better model at no additional cost or a refund of (purchase amount).  I have enclosed a copy of the receipt. 

I look forward to your timely response to this matter.   Please call me if you have any further questions. 

Sincerely,
Your Name