"I guess garages can get access to parts that joe public can't!"
Err not in my experience..
I had an offside ball joint fitted to my laguna before I took delivery of it..
It was a neccesary thing to rectify and it was highlighted on the RAC inspection prior to buying..
Well around 6 months later I found that the os balljoint also needed replacing.
Now as anyone with a similar experience will tell you.. You can't buy a replacement balljoint for a laguna II from Renault.. The balljoint is rivoted to the lower wishbone arm.. You have to buy the complete wishbone arm ( around £120 ) which I did and had it fitted by my friendly italian back street garage for £15..
Now getting to the point of my ramblings..
When inspecting the original repair to the n/s balljoint we noticed that it was a bit of a botch job.. The original repair was done on the cheap..
The knackered ball joint had the rivots drilled out and the replacement ( I suspect either a breakers part or maybe the eariler laguna ball joint ) was crudely bolted to the wishbone arm..
Be careful what you beleive of your garage. They may have shown you someone elses cv joint and without the paperwork to prove things you may have been fooled into beleiving your paranoid.
You have every right to demand to see the paperwork if you wish to question things and I would strongly suggest you go back and check.
I have called Renault and your correct regards the part so please do yourself a favour before you end up 6 months down the line with another bill to pay..