My electronic colibre lighter is not working as it should, I have been using it for nearly two years. It does not always show ignition. Where can I get it repaired. I live in Milton Keynes?

If this is a Gas jet torch lighter it probably doesn't have one. It uses an 'electronic' ignition which doesn't need a flint. These "piezoelectric' lighters can last for 10 or more years with no problems.
If it is working correctly you should hear a 'click' when you press the button. Gas 'torch' lighters tend to run out of gas more often as the flame burns more fuel at a faster rate to produce the 'Jet' flame. If it isn't lighting properly try refilling it first. These are generally considered a 'cheap' lighter so if refilling doesn't help you could just buy a new one.

Are you sure your Silverado is a 1994? The first model was a 1999 year.
The fuse for the cigarette lighter is in the engine compartment. A black box near the battery. I've attached an image to show the 2 most likely fuses you will need to check.

I don't know what year it is. But this video from youtube may give you an idea of how to do yours. You can buy electrical tape & a cheap screwdriver & needle nose pliers at Walmart. Wrap the screwdriver tip so you don't scratch your plastic like this guy did in the video. Use the needle nose to unscrew the nut, if there is one. The replacement lighters show just a Blade type; 1-prong male terminal. Have you tried just prying it out near the rim of the lighter? https://www.youtube.com/watch?v=CmwXCBo2M9k&list=TL22RiG_zP4oVIBeL9_yKdcKytU23ZZ3o0

You have to find the fuse for it, check the fuse, and if OK, then you have to check for power and ground at the socket to find the problem. Youtube probably has a video how to use a voltmeter or test light to check for power and ground.
Those cigarette lighters almost never used to fail. Good for years and years. But now with all the devices people can stick in them, they have problems pretty frequently. Maybe an overload in some cases.

Yes I think. The fuse cover may show it or car owner's manuel

Do you know for a fact the cig lighter element is not the problem with the blown fuse ? Have you tried using the outlet for powering something else ?
And what is the make model and year ?

some of these use a fueable link wire near the connecting block under the hood also.. be checking this too if in doubt though you can always rewire these fairly simply

This is a common problem. Your alarm was on when the battery went dead. When the alarm activated, the hood/bonnet opening lever locks to prevent thieves from opening the hood in case the top is down. Some boxsters have a jumper post the pulls out near the fuse box. However, I do not think the 1997-1999s have this post.

Buy a male-to-male cigarette lighter adapter at the auto store. Connect between your car's cigarette lighter socket and the other car's cigarette lighter socket. Do not try to start the ignition or the any other electronics. You should not even need the key in the ignition. You should be able to pop the door locks with the remote and open the bonnet.

You may also need to recover your radio code: http://www.a2dvoices.com/realitycheck/porsche/

There are two ways of going about it. The best way to do it would be to use a relay. Cut the 12v+ wire going to the cigarette lighter, hook one side up to terminal 87 and the other side to 30 of the relay. Ground pin 85 and hook up pin 86 to a switched ignition wire. Doesn't matter too much which ignition switched wire you use. The radio is near by and has a switched ignition wire you can tap off of. The relay draws very little current so it won't affect the other circuit. Doing it this way keeps the power to the cigarette lighter on the original circuit, but switches it on when the ignition is on. You can purchase an automotive relay like the one pictured at radio shack or any auto supply store for a few bucks.

You need to replace the lighter socket. Both of my 1988 S10's had the same problem after a few years of using my cell phone battery charger in the lighter plug. I replaced it 10 years ago and it has been fine ever since. Something in the original socket wears out and causes it to short out when something is plugged in. Good luck!