I have had the occasional lens error. In many cases cleaning the lens contacts did the trick.
One thing that does not instill a lot of trust in me is the fact that these lenses are big chunks of electronics without having much control or possibility to tweak yourself.
The lens that gave me the most problems was the HC35. After having cleaned its contacts I cannot recall that I got another lens error.
Sure it can always break and be in need of real repair. What was wrong with your HC100 and what did they repair?
i wasn't told what they repaired but on the receipt it says "belichtungseinheit erneuert" which translates to "new exposure-module installed". whatever that means
i had the same problem with the 50mm i have, but after turning the camera off and on a couple of times it started working again. it can't be dirty contacts because both lenses are brand new and it happened on the first shoot.
by the way, i have an h2 not an h3d, so there may be a difference here.