the rear took the full hit when going up the
kerb. This has caused an indent in the rim or 'flat spot'. In part
this is becuase the shop did not sufficiently tighten the spokes after
purchase

If it's a dent in the rim it's more a combo of too little pressure in the
tyres, not shifting weight off the back wheel on impact and (of course) the
kerb. There're a couple of reasons why I run my road bike's tyres at full
pressure, and this is one of them.