That is a real shame, I have been on the Harz system a few times and it has always been fine. Like one of the above posts, I was on a train coming down from the Brocken when the loco failed, but they sent two locos up with a train coming from the bottom and one of those detached from that and was shunted on tour ours and took us back down. It was fine. I hope you try again with success next time.