Hopefully someone knowledgeable could help me? 
Our shower keeps losing water pressure - it will initially run very well then go to a trickle. I've stopped using it as I wouldn't exactly call it a shower now! There are no issues with the pressure in the bath or any taps. The shower is run off the boiler so not electric (which is a 29cdi combi if that helps...)
We've just had a new boiler put in - which has not yet been signed off because the gas pressure is too low so we have to get transco to put in a bigger gas pipe but in the meantime we can use the boiler sensibly thank god. Our old boiler died about a week and a half ago and I'm tired of kettle washing!!
Does the low water pressure have anything to do with the low gas pressure? Or is it likely to be a plumbing problem? Any suggestions on home remedies before I add to our already massive expensive to call out a plumber? 
Any help would be gratefully received