I'm going to echo this. "Please" implies an optional action like when you're trying to be kind to a child. As an adult some people will need you to do things unequivocally. If you can't handle that then that's really unfortunate for you. Please, get over yourself and understand that sometimes business is business and some thing must be done. They aren't optional. Otherwise you may find yourself finding a new job.

Having said that, I think it is wise to try to keep things amicable and only fall back to more rigid language and requests, stated as requirements, only after kinder communication has failed.