@Ann56 Half a day without hot water is enough of an inconvenience to warrant some percentage of refund off that night's stay - but how much is fair depends on how many home functionalities it affected. If the dishwasher, laundry, and room heating were still in working order, the only issue at hand was some delayed showering. For that, I'd offer something like 20-30% off one night's rental before the guest had a chance to mention a refund. If they ask, I'm inclined to be less generous.
Two nights of totally free use of all your home's facilities is a wildly excessive request, and I hope your review takes note of the guests' audacity in asking for it.