The following is a conversation I had with one of my customers a couple days ago:
Me: Hi, Mr. Customer, As I talked about with you last week, you have outstanding invoices from February of this year. Last time we talked, you said you were going to send the check out. Do you have the check number?
Deadbeat Customer: I sent the check already.
Me: Great! Thank you! Do you have the check number?
DbC: I sent it out already.
Me: I know, thank you, do you have the check number?
DbC: Do you not trust me? (getting noticeably angry) I told you I sent the check out, I have been doing business with your company for how many years.
Me: I understand, and I appreciate that. Certainly you realize that merely "doing business" with someone for a given number of years doesn't release you from your (legal) obligation to pay for the services offered, in a timely manner.
DbC: I TOLD YOU I SENT THE CHECK.
Me: I know, but since the check won't be here by the time it needed to be, I was going to give my manager the check number, amount, and the date it was sent, with the hopes of keeping you out of collections.
DbC: I don't have the check number, this is getting very annoying.
Me: Paying your bills is annoying?
DbC: No, you always calling me about my past due balance is annoying.
Me: So the expectation that you pay your bills is annoying? I find it to be completely reasonable.
DbC: I want to cancel my service with you, this is ridiculous.
Me: Sir, our service provides you with over a 6 time return on your investment. Please don't let your anger fuel a kneejerk reaction that would ruin one the most profitable marketing programs you're using.
DbC: *hangs up*
Wow, what a dick.