Is it possible to change the door furniture on a composite front door?

[Teapotblue]

Our front door is very tatty, and I'd love to replace the letter box and lever door handle. The front door is composite and has a three point lock, has anyone done this and is it feasible to do as a DIY job? We've always had wooden front doors previously so I'm a bit clueless about composite ones. If its feasible could anyone recommend a good supplier for the hardware? TIA.

Watching with interest. Someone (postman?) took a severe dislike to our letter box and scratched the hell out of it and it looks dreadful. The mechanism in the door handle isn't working as well as it used to and the coating on the metal is pitting as well. It's really irritating as the door is less than 10 years old, and at the price of it, I'm a bit disappointed. The door itself is fine.

I feel your pain @shoofly. Yes, ours looks very tatty indeed, and I don't think its particularly old either (it was there when we moved in). I'd like to replace it eventually, as I also find its absolutely freezing during the winter; but I figure a spruce up will help in the meantime!