This is an ongoing concern for owners of cars that were built in places that simply don’t have the UV radiation levels we experience in Australia. And, yes, I know your car is a Holden Calais, but the ZB model you own was actually built in Europe and is a fully imported car. That said, even local car-makers have had an awful time over the years trying to get their paint to last in the Aussie sun.

However, I don’t believe that a 2018 car should be showing signs of paint degradation this early, so I think you’d have a very chance of making a warranty claim to have the problem put right. Even though Holden no longer exists as a brand, its parent company still has an obligation to provide parts and service (and warranty) for the next few years. That said, there’s not much in it for General Motors to keep you happy as you won’t be a repeat Holden customer (since the brand is gone).

But it’s definitely worth a try and if you don’t get any satisfaction from head office’s customer service division, I’d be talking to the ACCC (what used to be Consumer Affairs) to see if a resolution can be found. It’s difficult to diagnose problems by remote control, but if the paint is peeling in a very specific section (the drain channels) rather than randomly on the roof, then it would seem as though there might have been a production problem when the roof was painted. If that’s the case, what’s left of Holden should put it right.

THE VT was a good solid car when new, but is an ageing model now, so you need to be careful about many things. Look for evidence of a crash, make sure it's been regularly serviced, and have it driven by someone with experience to make sure all's well mechanically.

OUR aircon expert, Mark Lynch of Carcool Airconditioning, says your problem is caused by a faulty vacuum switching module, which is a common failure for a VT. Unfortunately, Mark says you will have trouble finding a new module and that fitting a module from a VX or later model requires lots of work because its a six-switch module that requires a modified vacuum loom, whereas the original was a five-switch module that is no longer available from GM. Mark says the best option is a second-hand one.