Had that recently, I configured a modem in a particular way, checked it looked ok and sent it out.
The kit arrives on site, and I get a phone call asking why I'd set it up for PPPoE rather than DSL. "Oops says I, I must have done that on autopilot, let me just look up the correct details".
I look in the ticket and see that the very person who rang me up had left a comment instructing me to use PPPoE.
They were suitably apologetic when I pointed out that I'd done exactly what they'd asked (turns out they forgot to update the ticket when the requirements changed).