Triton t80xr electric shower low pressure light on?

Hi i own a Triton t80xr shower unit,i switched it on this morning and the low pressure switch came on,there is a flow of water but it's not as powerful as normal and it does not heat up.
I noticed the low pressure light was flickering in the last few days.
I went to the kitchen to check the flow of water there and it's not as powerful as it has been.
Is the problem with the actual unit itself or is the pressure of the water coming into the property the problem?,any help would be much apprieciated.