Because human nature is involved, some decisions not to abandon a bad approach or program are very much driven by ego. Some managers feel that to change course or give up on something that isn't working is akin to admitting failure. Keep in mind that management and decision making is an art, not a science. All managers make mistakes. The good ones are secure enough about their abilities that they can readily admit when they make mistakes.
Some managers are just plain stubborn.
Look at the situation as objectively as possible. If something isn't working, don't be afraid to admit a mistake was made, make the necessary corrections and move on. It is critical to provide outstanding customer service. The impact of customer service on profits is sometimes subtle and difficult to measure, but it is significant in terms of customer retention and sales per customer. Businesses that understand the importance of delivering outstanding customer service on a consistent basis and that have the proper market strategy are typically far more profitable than those that do not.