intermitant brake failure 307 hdi?

How stupid are you? Your brakes are not working and you are still using the car? You post it on a website instead of getting it repaired?
I can only hope that if you do crash it is in to a tree and not some poor sod just driving up the road with the family.

unbelievable
November 2009

if pedal goes down to floor then it sounds like brake master cylinder needs changing, if pedal goes hard with little effect on braking then it is a vacuum fault,either servo or vac pump/vac pipework/one way valve that is at fault.[i take it you have checked fluid level in master cyl-ruling out fluid leaks,also a very badly worn wheel bearing can cause excess travel on first press of brake pedal!]

k
November 2009

sounds like your servo is on its way out........

me
November 2009