OY! Must be in the air...
No real advice or anything, but MAN do I feel you!
I've been wanting to vent about some things I've had to deal with at the bike shop lately, but I didn't want to send out a negative vibe, or give the wrong impression... (but here I go anyway, hope this doesn't come across wrong)

For example, WHAT on gods green earth would make someone think it's ok to come into a shop and proclaim/ask "Well I buy all my stuff online from like nashbar and Jensen, but the idiots on the phone don't seem to know what they are doing. So if order the wrong thing I can come to you guys and you'll tell me what I need right? So then I'll know what to ask them for when I need to excahnge it"....
My manager who is normally SO restrained actually looked at the guy point blank and simply said firmly "NO"....
Yes, a guy actually said that pretty much verbatim!

Or the guy who rebuilds 80's style bmx bikes. He never so much as buys a tube from us, but he has no problem coming in and taking our mechanics attention away for 20-30 minutes at a time while he asks them to explain to him in detail how to fix something. Or he'll ask to borrow a tool??!!
Ok, I have no problem giving advice, or answering questions, but it has to work both ways. Give us a few bones every once in awhile. I pay my staff PER HOUR whether they are doing something earning me revenue or not. And when you take them away from whatever is on the stand, you are also cutting in front of the person who IS paying us for our services!

WOW. I feel MUCH better!
Sorry to hijak this thread, but it's kind of related as to why sometimes dealing with the public can be so frustrating.
Tho I must say 99.9% of the folks who walk in my door are fabulous!
It's that .1% that grate on my last little nerve!
I'm sure it's the same way in your class.
Sigh.... (shrugs shoulders)....