Hot / Cold Water - Worcester Greenstar 37CDi Combi?

When I turned the shower on this morning the water went through bursts of hot water for about 1 minute then cold for about 1 minute and so on. I am pretty sure this is related to the pressure in the boiler as it looks very low, but does anyone have any solutions or experience of this?

It's a fairly new boiler as far as I am aware, but you can never be too sure!