re: '"column locking device"
If it's anything like the Xantia's it just MAY be the actual securing tightness of the adjustable column onto the instrument binnacle/column housing. There's 4 nuts that hold the main column onto 4 studs off it and it could be argued that the steering is in jeopardy of failing in an interesting fashion IF it's all loose. Guess you'd notice this one yourself mind!
re: "Offside lower" If it's outside the car still on the steering column maybe the guy's starting to play silly buggers! There's a universal knuckle but that'd be called a swivel joint etc...
It wouldn't hurt to have a "chat" with the tester before wasting another 35 quid. I must say I've never heard of this part on anything before either. Jargon to cover an area of confusion or doubt/misunderstanding is always a good ploy - baffle with bullshit!
Always works for this government!
Andrew