why do Citroens have bad reputation with uk garages

[Father Ted]

I would have thought it was a bad idea to buy a car with hydraulic suspension anyway.

You have obviously never driven one.
A well maintained HP car will knock a conventionally sprung car into a cocked hat.
Google the old GSA adverts of the 70's with the "missing wheel" or "blow out" ads. The latter happened to me on a BX and I was able to keep control and drive the car to a safe place to change the wheel.
A lot of people who own gliders use HP cars to tow with as well, many caravaners will tell you nothing feels as sure footed as a HP sprung car when towing, not even 4x4's. And this is down to the self levelling ability of the HP set up.
I think a lot of the "French is s**t" perception comes from general ignorance in the 70's on how to maintain them. A well maintained and set up BX for instance is far more pleasing to drive than a Mondeo. Plus back in the 70's there was a lot of national press "Backing Britain" stuff going on and anything that want made in the UK was deemed to be inferior and crap. I think this has carried on in the countries mentality.
I always thought the Berlingo was akin to the 2CV in its design.