Well I got through to the appliance repair people yesterday and they said, "bring the oven along", so I reserved a car for this morning and we hauled said oven and ourselves off to the aforementioned place.
A kind chappie listened to our problem and then helped me carry the machine in and plonk it on top of one of those gas cookers with a folding lid.
"I can tell you now that we can't fix it;", he said, "it's a bit too old, they only carry parts for eight years, and by the time you track the spares down you just as well have bought another."
We surveyed the combination ovens they had in the store. All were too small.
We contemplated getting a small oven and small microwave separately. That would take up twice the room, the oven are particularly basic and in our experience don't last very long.
We contemplated getting a small electric cooker, sawing out the worktop to allow it to sit in the kitchen and getting a small microwave oven alongside.
Then we had had enough contemplation, so we went to Géant Casino to see what they had down there.
Not much, and all far too small, was the answer.
Home and the websites of Amazon, Conforama, Darty.fr, cDiscount.
Eventually we ordered a machine - it gets wonderful reviews, (apart from a handful of people who can't fathom how to turn the thing on) and will be delivered next Tuesday.
I just hope it's big enough...