Bizaarly this exact thing happened to me - my clio just stopped working out of the blue last week. It's been in the local garage since last Saturday - they could not fix it after trying nearly everything under the sun (and me posting lots on this forum to try get some answers). I too came to the conclusion that it must be the
and resigned myself to the fact the it was going to cost me an arm and a leg - however, we sent it to a Renault garage in the end who have now fixed it today!! It was a broken wire going into the computer that would have been hard for the local garage mechanic to get to. So instead of costing and
arm and a leg it just cost an arm...
Hope yours gets sorted soon too!