Why have a customer satisfaction guarantee?

You should have one so like if a customer isn't happy, you can guarantee happiness and if they are happy, you have at least one customer that can spread the Word. It is all based on these costumer's opinions and it is to make sure everyone of them is happy and satisfied with your product or whatever it is you sale. it also gives them a heads up that if they don't like the product/item, they can return and shop or buy something else in your store.