well they cant be much of a garage if they cant tell you which side is causing you the problem.
when i have wheel bearing failure its usually a whining noise when going around a left or right corner that determines which one is the problem.
but i have come across a strange one thinking it was my wheel bearing on a merc some yrs ago changed the wheel bearing and was exactly the same, had a puncture the same day whilst testing it on the same side so went to get a part worn and it sounded worse, so took it back and paid a drastic £110 for a quality new tyre, when i left there was no bearing sounding noise it was the tyre,
2 part worn tyres that did exactly the same, dont bother with part worns anymore