Another judgement day

Well, to update you, the mechanic (Moira) has "cleaned up the sensors" whatever that means.
Guess what? The problem was still there.
So back to the Fiat forum to ask for advice.Put simply, they collectively suggest 'hooking it up to a diagnostics machine'. Sadly I now know that the car doesn't have a socket to do so (at least that's what Moira says).
But the problem persists.
Tomorrow then is a showdown as Moira has suggested the car (which has no name - though my sons have started calling it "the tin can") needs a new 'throttle body'. What is a throttle body? See this scary picture from Wikipedia.
It seems this bit controls the air/fuel mix and it also has (depending on the car) bits of electrickery to tell other bits of the engine what it's doing.
Now I recall reading (in the handbook I think) that the Seicento is fitted with some kind of device to stop you over-revving the engine. Maybe this is it!
The showdown? Well, I'm going to have to tell the garage that the car is undrivable on roads over 40mph (and is therefore dangerous) and so, if this doesn't fix it...they'll have to take it back!
Watch this space.