vibration at standstill td6

hi guys
heavy vibration at standstill with your foot on the brake
dealer has tried every thing inc new gearbox
06 td6
18 inch wheels
any ideas
please help
mike

first of all i know nothing about this engine but if its when you put your foot on the brake it might have someting to do with the vacume pipe as i think the master clynder is liked to the top of the engine i think for back pressue some how. autos have a valve on this pipe. does the engine cut out at idle. is there any noise to this vibration i.e konks wining grinding. etc