Here's my tip for this section.
I had a non-functioning cigarette lighter socket. It was a bit of a pain as I wanted to use it to charge mobile phones and so on. I had to resort to using the auxilliary power socket in the armrest. I used a small torch to look into the cigarette lighter socket and noticed severe oxidation coating the socket contacts. I was going to take the car in to the dealer to get that sorted when I realised that, from my HiFi days, I had a can of DEOXIT D5 contact cleaner. This is a truly miraculous contact cleaner and dissolves any gunk or oxdiation on metal contacts instantly.
I sprayed a tiny amount onto a cotton bud and, WITH THE ENGINE TURNED OFF SO AS NOT TO CREATE A SHORT CIRCUIT, I dabbed the soaked cotton bud onto the centre pin contact of the socket. The DEOXIT D5 instantly soaked into the oxidation and dissolved it. It's important not to spray it directly into the cigarette lighter socket as it'll probably cause a short circuit when you turn the ignition on. Then, using a clean and dry cotton bud, I wiped away any excess contact cleaner. I also cleaned the side metal contacts (the negative terminals) of the cigarette lighter socket using this method, taking care not to bridge the electrical contact between the positive centre pin and the negative side contacts with any fluid. It took two minutes and I have what looks like a brand new cigarette lighter socket that works perfectly.
DEOXIT D5 can be used on all electrical contacts and chemically cleans the contacts and protects them from future oxidation. It's a pricey spray (around £17 for a can) but should last many years.