Your right Iain I should have done a search, this has blatantly been asked before. Sorry I did'nt think!
Gweebs maybe your right. But my understanding was that the standard heatshield is prone to coming loose (as every 172 seems to get the 4k rattle eventually!) so simply refitting it may mean it happens again. In that case getting an aftermarket one (hopefully better quality) fitted and being done with it may be best.
In any case I don't really want to go to Cardiff, can Kwikfit be trusted?