as with anything that relies on anecdotal evidence it appears all shops can drop the ball at some point in customer service, find a shop where you trust the staff
if you want decent service its best to avoid weekends or lunchtimes when staff are most busy
there are plenty of independent places i'd spend a grand
condor, shop 14, tokyo fixed gear, brixton cycles, cavendish, putney cycles
as with anything that relies on anecdotal evidence it appears all shops can drop the ball at some point in customer service, find a shop where you trust the staff
if you want decent service its best to avoid weekends or lunchtimes when staff are most busy
good luck