how to fix mixer tap, ideal standard, hot not working?

The hot water only dribbles out of the mixer tap in the bath. At first pulling and pushing on the tap got it going enough but now nothing is coming out, when we tried to fix it, it gushed and couldn't shut it off. Any ideas welcome? We are about to move so do not want to replace them and need a very quick solution (its 7 days to get a replacement cartridge thing). thankyou