IDEA: Tell customers immediately when they OVERPAY you. Do not wait until they call you!

Be trustworthy. When you get a check from a customer and it is not yours, get on the telephone, call them and tell them you received a check that is not yours. Do this before they call you. Show them you want their business and are to be trusted.  Do not make them call you to ask for the money to be returned.  If they pay the same invoice twice, call and tell them so they do not have to question your integrity. If you wish, let your salesman tell them but if you do, make him do it immediately. Do not wait. Whoever makes the call needs to contact them on the telephone and also in writing with an email.  You do not want them to wonder why you did not call when you could not match their paperwork to your books. When you get money that is not yours, call the payor immediately so they will appreciate your honesty. They want to do business with good people, not people they cannot trust.  You also never know whether it was sent deliberately or not.