There are a few possibilities here. The first is that there’s been a failure of one of the battery cables that connects the battery to the car. If one is loose, broken or badly corroded so that it won’t let current to flow, then it won’t matter how many jump starters you connect, the thing will not fire.

A second possibility is that there’s something gone wrong with the key fob or immobiliser that isn’t allowing the car’s electrical systems to fire up. Even then, however, you’d perhaps expect to get a red light on the dashboard when you hooked up the jump battery.

What about the jump starter pack you’re using. Is it fully charged? Is it still working (some of these units die suddenly when you need them the most)? Don’t forget that some battery terminals have a built-in circuit-breaker that acts as a fuse if the car’s electrical system experiences a power spike. These circuit-breakers can be replaced or sometimes reset to get the volts flowing again.

But possibly more likely that any of those scenarios is a battery that has literally fallen apart internally. A battery is a series of cells and, if one cell collapses or fails, the battery effectively stops being a battery as the missing cell acts as a circuit-breaker. At which point, you can hook up the world’s biggest jump pack or jump battery and nothing will happen. Change the battery for a borrowed one and see if things improve.

Your electrician has done the right things so far, Ken, starting with making sure that the battery is charged and being charged by the alternator and that the car is earthed (grounded) properly. Those are traditionally major causes of this type of problem, but unfortunately there are many more possibilities in a modern car with its electronics. My first thought is that the functions you’re having trouble with are all controlled by the car’s body computer. So I think that’s where your electrician should start looking next. These computers can develop software and hardware faults that allow for these random and intermittent problems. So maybe borrowing a body computer from the same make and model and seeing if that fixes your problems (and at least ruling out the computer) is a cost-effective way forward.

I’d also be having a chat to the workshop that replaced the steering rack to see if there’s any way that a connection or sensor related to the on-board computer could have been bumped or damaged during the rack-replacement process. It would certainly be a coincidence (and it’s possible that this is exactly what this is) if these problems started straight after the repairs, no?

With local production shutting down the big-car choices are getting fewer and fewer, but right now you can still buy a Calais if that's what you like. You can also buy an equivalent Falcon or Toyota Aurion. There are more expensive cars, from the likes of BMW, Mercedes-Benz and Audi etc. that would suit, but they come with a much higher price tag than a Calais. Others you could try are a Skoda Superb, a Honda Accord V6 Luxury if you're prepared to give up a little in size, and there's also the Chrysler 300C.