Unless the water has come up through the floor and somehow got into the seatbelt mechanism or parts of it, the most logical answer is that rainwater has entered through an open window, run down the seatbelt webbing and into the mechanism under the seat. Failing that, if the floor and carpet has somehow got wet in the past, some water may have leached into the mechanism.

The question is: how do you know this has happened? The pretensioners only ever fire in the case of a collision, so their condition is pretty much an unknown until you need them. If, however, you’re referring to the inertia-reel mechanism that locks the seatbelt when you pull on it suddenly, then I’m sticking with the open-window-rainstorm theory, as water could definitely run down the belt webbing and into this part of the seatbelt assembly. Failing that, the moisture could be condensation that collected if the vehicle had been stored in a damp environment for some time.

If it’s only the low beam light not working and we’re not talking about crash damage here, then you can change the globe at home. You’ll need a H7 replacement globe for the Astra, and the blown left-hand side globe can be removed by undoing a small, plastic access hatch inside the engine bay at the back of the light, squeezing the spring clip that holds the globe in its mount, and then removing the wiring plug. Then, you take the new globe and reverse the process, being careful not to touch the glass part of the globe as that can damage the new globe.

That all sounds pretty simple and it is if you’ve done it before, but it’s also a bit fiddly if you’re a first-timer. But before spending money at a workshop to have the globe changed, check out some of the bigger chain auto parts stores. Many of these have a free fitting service for things like wiper blades and globes.

You can always go to a dealer but if you've got the original key fob an automotive locksmith is probably a cheap option for you. You can read more details about how to replace your car keys here.