Unless you have cross threaded the centre nut (which i can't believe is possible) or have re-used the old nut (this always needs to be renewed) the bearing was either DOA or the garage pressed it in pushing the inner ring and hence damaged it, or the very last thing (since they say old bearing was very tight) is that the hub bore is too large, i.e. was damaged when they forced the old bearing out.
there isn't really any other possibility if only the wheel is loose and not the whole hub.
I would take hub out again and inspect if the out ring of the bearing is parallel to the bore in the hub, that the outer ring does not have play in the hub, if neither is the case then it's the bearing. if it's in at an angle I would ask the garage to get me a new hub and bearing since that is due to assembly error. if there is play between hub and bearing then hub is damaged, this could be because there was a damage before so more difficult to pin on anyone.
in that case go to scrappy and get yourself a used hub including bearing.... or get new aftermarket hub with bearing already pressed in
