combi boiler rsf 82et not working correctly?

my combi boiler is not working correctly, everytime you turn the tap on.its pot luck if you get hot water or not, The timer dial reads 88888 and wont reset.
also the central heating wont come on at all eccept for the other night it came on without anybody touching it , the room thermostat was switched to (0)
strange but true?, had to switch the mains off to stop it from roasting us alive,Could it just be that the timer needs replacing?