Ok, after changing all my blue badges to red ones, I thought I'd share the knowledge gained. Thank you to Punto Po, who I've shamelessly taken some photos from, due to me forgetting to do so when changing mine!

Front (Difficulty 1): (95mm badge)

This badge is held on by a bolt behind the grille, and the easiest way to get to it is just by removing the whole grille. Simply pinch in the corners of the top grille to free it and it should pop out nice and easy. I've heard of some being quite a pain, but just try freeing it all the way along as it's held on with many clips. Once you've got the grille off, simply undo the bolt behind the badge, and Bob's your uncle!

Rear (Difficultly 1): (85mm badge)

This badge isn't secured on and is just kept on with adhesive. To free this, carefully prise the edges (and be very careful - impatience with a sharp knife led me to chip away a tiny bit of my paint) until it starts to free, then just prise it all the way round. There are three little pins meaning you've got no chance of getting your badge the wrong way round.

Alloys (Difficulty 1 - Time 5!): (50mm caps)

Unless someone else has figured a way, the only way to remove the centre caps is by giving them a whack with something from the other side, which means laboriously jacking the car up 4 times and removing each wheel. Hey, at least you'll be able to give your alloys a proper 100% clean for once in a while! I'd recommend something rubber or plastic to whack the caps out so as not to scratch the alloy, think I used the other end of a mop for mine!

Steering Wheel (Difficulty 3): (55mm badge)

The only badge not easily findable. The only way I got mine was by contacting a breaker, who sent me it in return for £10 of my dough. A lot of breakers only want to send it with the airbag and everything and charge you a fortune, so it's worth emailing a lot of breakers. I received this in the post:

The badge is attached with teeth through the plastic as shown here:

The way I found of removing the badge was to simply cut through the plastic, which is soft enough, and then the badge will come out with its teeth intact nicely enough.

Once you have just the metal badge, it's time to go about butchering your car! The first problem I encountered when removing it was the horn constantly unexpectedly going off when pressing too hard, which is quite a pain when doing it on a busy public road. So I had a little search in the fuse box, and third time lucky I found the horn fuse which I've circled in the picture (marked number 36) (note: may be different for other engines, but this is where it is on my 1.3). Easily removed with tweezers, just make sure you remember to put it back in once you've finished as it's illegal to drive without a working horn:

Now, the only way to get the old badge off without a fight is by maiming it beyond recognition. Po's picture shows it quite well:

I'd recommend using diagonal pliers/wire cutters and piercing the badge initially in the middle as there's a little indent on the wheel there, from which you can then freely cut and prise the pieces of the old badge out. It's worth cutting it into many bits to avoid leaving bits of the old badge teeth still inside the wheel. Once this is out completely, providing you've cleared all the old badge teeth, the new badge should just clip in without the need for glue or anything! Voila:

I hope this has been of help, and good luck personalising your Punto! :)