I just received my new VDSL modem, on a post it note attached to the box was my current adsl password and the one i use for the snap site.
The fact that you have it in clear text is concerning enough (i'm sure you have a really good reason for that...), but then to be writing it down, and then sending it to your customer is just plain stupid.
Guess i'm lucky it wasn't stuck to the courier bag...