Ongoing woes - P2015 fault - VRS

So just over 4 weeks ago, my engine management light came on and local dealer found fault code P2015 as per previous thread

Roll forward to now, and I am still not able to drive the car as the dealer has not been able to find the actual cause of the problem - they've had the car in for "round 2" of diagnosis for nearly 2 weeks now. There's a lot of to-ing and fro-ing between themselves and Skoda Technical as to what to do to find the actual cause, they've had the inlet manifold off, everything so far has apparently looked OK. Noone seems to have a clue, and all the while I'm without my car (I finally managed to get a courtesy car last weekend after 3 weeks, which I've still got thankfully).

Always been very happy with Skoda up until now, and love the car but really fed up with the situation now.

Has anyone else been in this situation before? I don't think I'm being unreasonable in thinking that 4 weeks (and ticking) is an excessive amount of time to get to the bottom of it?!