If you criticize bad products and services, you must also commend good products and services. Companies want customer feedback both positive and negative. That's how they improve their products and services. Assume they want your feedback and give it to them whenever possible. Sometimes it's difficult to know who in a company is interested in your feedback.
Managers generally care more than staff and owners care more than managers.
When communicating your criticism never let anger get in the way of your message. Anger will hurt your credibility and your message will not get heard. Most customer service people can exercise a great deal of discretion when dealing with customer problems and angry customers seldom benefit from it. When thinking about creating a personal boycott, carefully think through the personal boycott steps . And remember the written word is more influential than the spoken word.