Think I've got a problem?

I have a Sytemate2000 and an Ideal Slimlineclassic SE15FF boiler, both put in when the house was built about 12 years ago. The boiler is set on maximum.

I have a three story house and the thermal unit is on the 2nd floor. The radiators appear ok, however the rooms at the top of the house never seem as hot as the rest of the rooms, even though the radiator thermostats are turned right up.

Hot water seems to be fine, although if both showers are being used at the same time the water does go cool.

I was told that to increase the heat at the top of the house I needed to turn the valve on until the pressure bar is by the red indicator. At the moment it is at zero and when I open the valve nothing happens (it used to make a sound and the black needle moved). I checked the grey water tank and that was practically empty, so I have filled that to the water line, but nothing still happens when I open the valve.

Do I need someone to come and have a look at it?

Get someone out.
Mike