David,

I don't want this to sound silly, but have they actually failed? Is there a chance that they needed cleaning?

 

I'm onto my fourth wastegate solenoid in 2 years now. What on earth could be causing this ?
I've heard that an engine overfilled with oil can cause this, but it's never been the case when mine have gone.

As the warranty is starting to run out on the car, I'd like to see if I can get to the root of the problem !

Either that, or I'll just trade in for a P1