Got my S60 auto back from the garage yesterday - gearchanges had become
intermittently quite snatchy, and a couple of times it seemed to slip
momentarily into neutral. All fixed under warranty, but when I asked what
they had done, they said they had changed the "control valve unit" (ok,
seemed reasonable), which uses "gases produced by the gearbox oil". Huh? Is
this this:

a)  Don't baffle the customer with technical details he won't understand;

b) Reception guy didn't understand what the mechanic told him, so make
something up for the customer;

c) Clever autobox engineering I've never come across before?

Ok, perhaps all boxes work this way, but can anyone enlighten me as to what
they were trying to describe?

Tim