Inconsistant Brakes

[pragmatix]

Just had my  2018 reg Grand Cmax 1.5tdci into the dealers fot inconsistant  braking, after a time not using the brakes in my case around 20 miles, when I put my foot on the brakes there is a delay before anything happens and I have to reapply the brakes, the dealer says there's nothing wrong and no fault can be found, interestingly the courtesy car I got a Fiesta 1.1 on a 17 plate did exactly the same, (by the way that's a horrible engine give me the 1 litre any day).

Anyone else come across this? It's very disconcerting, never had it on any of my Ford's before or any other car for that matter, well actually when I was racing and rallying but that was in extremis ( pad knock back)