If you are having a problem with company product or service then it is frustrating and annoying. When you endeavor to resolve the problem with the company then at first you require discussing your concerns with the company business representative. If a phone call or an email does not resolve the problem then consider sending a formal complaint letter to the company. The significance of a complaint letter lies in the fact that the document puts your complaint on record with the company and it helps to preserve any legal rights that you possess in the situation and also lets the company know that you are serious in pursuing the complaint.