I have so far had very consistent and pleasant experience with Air Canada concierge service in Frankfurt, over the past few years.

Back in the spring, my YYC-FRA flight was delayed, and pretty much I missed (by 5 mins) the connecting Lufthansa flight to Saudi Arabia, one AC lady waiting at the gate was more clueless:"you can try to run to your gate to see if you can make the connection..." and I did so, but only saw the plane was being pushed back. When I returned to find an Air Canada concierge, they told me that they were indeed paging me at the gate but missed me. So the idea is that they did have a concierge, but there were a few AC agents at the gate handling many missing connections. From then on, I would just check at the arrival gate to find the waiting concierge.

So far for AC FRA concierge services, I only have thanks, not complaints.