@Morgan166 How long did the guests wait to let you know the electric seemed wonky? As it only takes a few minutes to replace a fuse, unless you live far away and couldn't get there to deal with it as soon as you were informed, I don't see why it would take 24 hours to remedy. So if they didn't let you know first thing in the morning, they bear some responsibility for the long outage.
I agree with Emilia that being without a bathroom light (which they wouldn't need during daylight hours if there's a window there) and only having one TV to watch (oh, the horror) can hardly be considered some major issue and better guests would have just let it go.
I'd offer 25% for the first night- if that's not good enough for them, too bad.