Background
I work as a developer in a software development department with three other developers and a manager. We have a desktop application that is being modified constantly based on customer needs.
Problem
Recently, one of our customers asked for a modification to a feature that is already present in the product. It requires couple of more mouse clicks to get the job done.
My manager wants this modification to be implemented per the client's request.
I clearly explained a few times that we already have that feature and it's working fine. Also, I explained the technical impact of changing the functionality. My manager wants me to proceed with the change per the client's requests.
Question
How should I proceed?
Should I explain the situation again? Or maybe look for another job? Or should tell my manager that if it's so simple he should help out?
UPDATE
Every answer for this question cleared one thing for me: I need to change my attitude.
As almost everyone pointed out: I am not the manager, as long as I inform my manager the technical downside of a request, I should not judge. Also, resigning would be a temporary solution, as problem lies with my attitude toward the job and manager.