This sounds like a body computer problem. The body computer is the brains that controls a huge range of features but, tellingly, also the climate control and entertainment systems, as well as functions such as the wipers, central locking and much more. These computers can sometimes fail and require replacement, but sometimes they can be rebooted or 'returned to factory settings’ to use an IT term.

The easiest way to do this – not to mention the cheapest – is to disconnect the car’s battery and leave it overnight. It sounds odd, but this will sometimes force the reboot it needs to begin operating properly again. It doesn’t always works and even if it does, the effects may not be permanent. But it’s well worth a try before you take it to an auto electrician or specialist.

It sounds as though the transmission itself has encountered an internal failure for that level of mayhem. Diesel versions of this model Mondeo were fitted with a six-speed double-clutch transmission otherwise known as the Powershift transmission. With a wet-clutch design, this gearbox was a lot more durable than the dry-clutch design used in many other Fords including the Focus and Fiesta, and the latter was a complete disaster with premature failures earning Ford Australia a caning at the hands of the ACCC.

But even the wet-clutch Powershift must be considered a liability to some extent, and failures like yours are absolutely possible. This won’t, however, be a cheap fix and you can expect the repairs to be a good chunk (if not more than) the retained value of the car. At which point, you have to make some very pragmatic decisions.

If you’re lucky, a transmission specialist might be able to determine that the problem is a simple one and fix it cheaply, so that’s worth a shot in the first instance. But don’t be surprised if the diagnosis is a lot less rosy than that.

I'll take a punt here and suggest that your car is the turbo-diesel variant with the six-speed dual-clutch transmission. The dual-clutch unit is vastly more problematic than a conventional automatic transmission and has given many manufacturers (Ford and VW being two of the main ones) all sorts of consumer grief over the years.

The unit in your car is a wet-clutch design which is much more robust than the cheaper-to-make dry-clutch type, but has still been known to fail. (The dry-clutch units on Ford's Focus, Fiesta and Ecosport models cost Ford millions in fines when they began failing at low mileages and the ACCC stepped in.) That said, the wet-clutch units have also experienced problems, but before you scrap the car or shell out $15,000 for a new gearbox (which sounds like an ambit claim in the first place) have it checked out by a specialist. In many cases, jerky progress like you're experiencing can be caused by the transmission's control module or even a faulty speed sensor inside the unit, rather than the actual transmission hardware. If that's the case, it may be more economical to repair the car.

Beyond that, I totally agree that less than 100,000km is not an acceptable lifespan for a major component such as a car's transmission.