Passat TDI Brake problems

[Veedubandy]

Hi, I've had some problems with the brakes on my 1.9tdi b5 passat estate. I did the rear discs and pads not too long ago so they're fine but today I changed the front discs and pads. Now when I press the pedal it goes all the way to the floor, it only seems to brake on the second push then the pedal becomes rock hard on the 3rd push and it doesn't seem to be gripping. Then When left unpressed for a few seconds the pedal drops to the floor when pressed again, it's as if the pistons are going back in the callipers when the brakes aren't being pressed. Is there anyone out there that may be able to tell me why this is happening or what I've done wrong? Any help/advice is appreciated as always.