It's the same over here. It is basically caused by the low level of wages, another effect of the undervaluation of this trade. It is hard to get tallented people for small money and even harder to get them to care.
As regards your car, all you prove by applying vac is that the Engine, Turbo ect can make the power. What you need to find out is why it does not, doubtful to be a mapping problem unless every one of them is like that.
Why not let one of your more knowledgeable tech customers have a look at it.
Regards
Alan
P.S. As an aside, since Camberley own the car and taking block exemption into account why do you keep sending it to a dealer for poor service?