When is a time you should not pay for someones services?

When they fuck up something even worse. In 2006 I took a favorite pocket knife, worth $95, to a newly opened cutlery shop in Las Vegas to be sharpened, they ground the curved edge straight. I told them I refused to pay and demanded a replacement of equal value. When they refused I called for police assistance, they told the shop owner to replace my knife or face charges of false advertising. One year later the shop was closed down, apparently they had many more similar complaints and the city refused to renew their business license.