My "general attitude" is that I've never heard of anyone being told to go back to the garage to question the work of a professional.
And that is the big question, is it professional enough or isn't it - impossible to tell for me, but there is loads of garages out there that isn't - even if they are connected to Bosch etc. Have a few of them around here too, poor service and most problemcars is just sent off again with a bill of various sizes.
So, I'm sure that you can understand that I question your statement when you're the first one that tells me that the Bosch equipment is actually capable of possibly producing meaningful diagnostics.
From what i've seen a professional Bosch garage have very good equippment and access to highly skilled technitians backhand. They also have a big central database where they log problems and known issues. This is where such faultcodes sometimes
may be found along with problem and solutions.
Especially as I would now have to go back to the garage, confront the people, that probably have been trained in using the equipment, to tell them to dial home to the mothership and ask for an explanation. IMO that should have been done by default and thus I would assume that they'd exhausted that option, if it existed.
Agree - but still they might lack the habit of using the available recourses, depends on their true eager to serve and fix...
Now I might have go back to the garage and and yank their chain even more.
I would not hesitate to ask further - but by all means, it may not give any more answers and then Renault diagnostics comes next. I assume (hope) they didn't delete the faultcodes for you this time