I get this a lot, because I work in IT. It seems to be the one profession where your services are expected for free; if I had a pound for every friend-of-a-friend-of-my-mum's-hairdresser's-cousin who'd gone "oh, my computer at home is running a bit slow" I could retire. You wouldn't expect a plumber to come fit a new bath for free, so why is it expected of geeks? Because we're all stupid enough to keep doing it I suppose.
Anyway, before I descend completely into rant mode, where I'm going with this is, do the people you help appreciate it?
I don't ask for money when I look at PCs for people, but I appreciate it when they offer some form of payback for my services. It's nice to get a couple of bottles of wine or a single malt in return when I've spent all weekend off and on fettling something. It's got to a point now though where some people clearly take the proverbial, so my policy now is that I'll look at anything once, but their attitude when I do will wholly dictate whether I'll ever look at something twice. I don't mind doing favours for people, but I don't want to be openly taken advantage of.
The situation posted by the OP, the telling line for me is "when I needed help, they were busy" – that could be genuine, of course, but it'd leave me with a bad taste in my mouth personally. I don't do favours on the proviso that they are then indebted to me, but as someone else said this has to flow both ways.
