low boost and poor fuel consumption

[marks carlsson]

good morning all,
have a problem with the carlsson in that the turbo boost gauge shows that the turbo is only boosting about 3/4 of what it should be , meaning its at the 3/4 mark on the green part of the gauge and not going into the red and it seems to be holding back , is there any easy answer for this problem and also i seem to be getting really poor fuel consumption , around 19 - 20 mpg on all sorts of runs , shown up on the trip computer.
i cant see if there is a fuel leak but if i put a tenners worth of petrol in the trip computer shows the mileage to be about 50 till it will be empty again and this doesn't seem right to me as other people talk about getting 27 - 30 mpg fro the same sort of car
anyway one good point, went for the mot on monday last week and she sailed through without a problem which was a bonus
hope you can all help
mark

[marks carlsson]

TRIED THE CAR SAT AFTERNOON AND BOOST WAS GREAT GOING INTO THE RED ,
10 MINS LATER BACK TO NORMAL
PLEASE HELP