I was given the impression that it was against the law to discuss a business matter with someone other than that person. Of course my boss might have just told me that to keep me from doing it
But where I work, when I do collection calls, I am not even allowed to speak to the spouse of the person about their account (unless it is someone that is a repeat customer and we are 100% sure that they would not mind).
Of course sometimes we bend this rule. For example, if we have two sisters who both have accounts. Sister #1 has had her phone disconnected and Sister #2 is in the store making a payment... more than likely, my boss will ask #2 to get #1 to come in and pay as well.
Either way, I agree... it's bad business, but the guy sounds like he was being a complete jerk anyway.