Client: I didn’t want XP; I wanted Vista.
Me: But you asked for XP.
Client: But I want Vista now.
Me: I’m sorry sir, but you signed the form; it says right here in bold letters that there is no return on software.
Client: I only signed it. I didn’t read it.
Me: Again, I’m sorry; but it’s in bold letters for you to pay attention to it.
Client: Maybe YOU should pay attention!
The client then grabs the form from my hands and runs out of the store. Three minutes later, he comes back in silence.
Client: …I left the CD
He then apologized and returned the form.
Another "why buy a wheel when we can reinvent it!" moment, from the Clients From Hell archives.