Glowworm 30cxi boiler - pressure keeps dropping and excess water?

hi my boiler keeps cutting out which i realise is due to a low pressure, when i follow the instructions to turn the filling tap underneath to the left water poors out and quite a bit. eventually the pressure comes up but its stuck at 0.9. the water shows no sign of slowing down, while the filling tap is released, should i keep draining or has something broken.
would be gratefull for any help