I have a Cayman S which basically has almost zero braking maybe one time in 20. On the other occasions it brakes ok.
When it doesn't work properly the pedal stays firm rather than going to the floor but just doesn't slow the car down properly
The front discs & pads were approaching the end of their life but there was no odd braking noises / other signs of a fundamental problem
I asked the garage to check it out & change the discs & pads.

Their assessment is that there is no obvious fault anywhere in the braking system, having checked everything over (fluid fine, no sign of leaks, master cylinder ok...)

They can't replicate the fault but having changed the discs & pads say the brakes are miles better in general use
Has anyone had a similar intermittent problem or have any ideas what the problem might be - I am surprised that just changing discs & pads has solved this. I don't have any idea what to ask them to do next / how to isolate the problem