How can I flash my Renault scenic ECU?

Hello Guys,

I have a 2003 Renault Scenic 2.0L Automatic, the problem is that the dashboard gearbox icon would light up
and the box would kick down into 3rd gear.. (frightening experience at 120 KPH), I would then need to
switch the ignition off to clear the fault, this happens mostly but not always when the oil is cold.
The Company that specialises in gearbox repairs have replaced the old box with a reconditioned box, but
after a week or so the problem returned. they have now ordered a whole new valve assembly, and will be
fitting it next week, but I'm not convinced that it will solve the problem.
I read on one of the Renault Forums that this is an inherent fault with French Automatic Boxes, and to
solve the problem is to replace the EMV valve sensor and flash the ECU with firmware telling it to ignore
the sensor problem, I mentioned this to the owner of the Company, and was told that even the Renault
experts in South Africa don't have the equipment and knowledge to facilitate this course of action, so his
response is to fit the new valve assembly and hope for the best. Is there any way of me obtaining this
firmware and the means of flashing the ECU to resolve this problem.
I am really desperate, as I'm afraid to drive this vehicle on the freeway for fear of damaging the box and
whatever else, I would be indebted to you for any help and advise you may have.

Kind Regards,
Alan.