Providing feedback isn't much, but it's better than nothing. Closing an account and going to a competitor is another option, if competitors were not as bad.

I can't talk directly the person responsable, the employee is more likely to be able to.

I was once an employee in a similar situation, getting feedback/complaint from a customer. As an employee you can't do much if you alone think management is making a dumb choice. But if a (enough) customers thinks and say it, employees who agree may jump on that occasion and sens that feedback to management.