Just the Commas, Please

So how do you guys deal with it when someone comes in and just wants to go over their punctuation? I mean, I feel pretty capable to give them some quick advice on a few rules, even though Penny would discourage it. And I feel bad trying to force them to discuss content when that's not what they want.

Students really don't have anywhere to go to ask grammar (by which they usually mean punctuation) questions: writing teachers don't cover them, Erica's hours are extremely limited, and our lovely handouts can only take them so far. I know we're not an editing service, but what's a student supposed to do? I feel so bad for them. Ideas on how we can better deal with this?