Think I'll be changing my wiring to a safer arrangement!
This looks a bit strange to me. I just checked the ones in stock and we do have the active up to the switch and then neutral going through the elements when the boiler is turned off. I am not sure when you purchased this one but for the stock that I have checked in the last few batches from Feb until now are all wired with the active to switches. Is it possible for you to send us your order number so we can look into that batch that you have got. It must have been from stock manufactured before Feb 2020 but I have none of this older stock at our premises to be able to check so it's only a guess.