Update, as people here have been very helpful and curious
It's now been 4 weeks since the PCB was replaced, and we've not had a single hitch since. It could be that the problem has been solved. I say this while I touch wood, cross my fingers, etc etc, of course.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local