A complaint letter in general used to report anything that works in a wrong way. For example, you may buy a product from a good dealer, but it may malfunction on the first day of its use and you can use the complaint letter to inform the dealer about this and also to claim for a refund or repair service if you have warranty. Check the template below.
Dear Mr./Mrs. Name,
I am Madan writing from the state of Michigan. Yesterday I bought a electronic gadget from you shop with a warranty of one year. Unfortunately, the electronic gadget is not working good anymore and it spoiled my another electronic gadget coupled to it.
Since, you have a big and reputed dealer ship with good customer service, I request you to repair my malfunctioned gadget or to replace the product under warranty. Details about receipts and warranty card is enclosed with this letter.
Kindly make this service as soon as possible, so that there is no need for me to approach a solicitor or consumer group.