Hi there, thanks very much for responding. Yes when I picked the car up the first time I had to pump the brakes occasionally to ensure I could stop. Since then they have done a full brake fluid change and bled the brakes and did it again after they fitted the master cylinder. They did say to me that there is still air bleeding out of the system and still it hasn't changed anything. They have also checked all the brake lines and seals and said all is fine. They think it could be something to do with the vacuum system but I don't know what that means. I am still can't see how such an easy job is causing so many issues. I still don't have the car back to check how it drives and if indeed it can be driven.