"It should have been checked out"? - no, the buyer should have had it checked out if she had concerns - caveat emptor and all that. It's a PITA for the buyer, but I'm quite sure she will paperwork stating that 'the CH system has not been checked and the prospective purchaser should satisfy themselves it is working before exchanging contracts' or something, - she's gambled apparently unsuccessfully on saving a few quid by not having the check done.
If *I* was buying a house I would certainly want to commission my own inspections of whatever services etc I was concerned about - do you really think it's OK to rely on a check commissioned by the vendor, who can commission 3 or 4 inspections and only produce the one which fails to spot the fundamental flaw which he doesn't *really* want the buyer to find out about? That's the fundamental problem with this 'buyer's pack' nonsense.
David