I think they mean you turn the steering wheel a little bit and the front wheels don't move. There's not much in the shaft that could do this. Look inside the front wheel arch where the shaft comes through the bulkhead, it has a splined join which is clamped shut. Make sure there is no play there. There's also a small universal joint a bit further down, check play there. And finally where the shaft joins the steering rack.
Other than that check the steering rack is mounted tightly. Get someone to turn the wheel while you hold the rack. Does it move? Could be knackered bushes. They're a pig to change!
If not that something in the rack itself?
You'd hope a garage would know if it was something as simple as tie-rods.
If all else fails get it tested somewhere else? Good luck!