Honesty and reasonability
As a consumer you must be honest with a business, so it can be honest with you. Most consumers are honest. Dishonest customers shoplift, don't tell the truth when returning an item, and may not be honest when paying for products. These are crimes and are an expense to businesses. The businesses lose billions each year and make up for this by charging higher prices which affects all consumers.
It is important and necessary to complain about a product when you have a problem with it, but you need do it in a calm reasonable manner. You also have to make sure something is wrong with it before you complain. You need to be able to tell a full explanation of what is wrong. Have a positive attitude while talking, shouting and being angry will not help the situation. If you cannot get a satisfied response you should go to the owner or boss of the business. You could also write to a organization like the BB about your problem. Being calm and formal will help get the solution you want. Most businesses are happy to fix a problem a consumer has.