obc (+HNY)

first of all, happy new year and thanks to everyone who has helped me to keep that jalopy of mine going last year.

let me ease you lot back into it with what i hope is an easy, hangover friendly one- One of my new year's resolutions is to sort out that ugly OBC of mine. i have a 7 button obc with a dicky display. can i replace it with an eighteen button equivalent? i've searched this forum but the majority of people trying to fit these are replacing their analog clocks and have no obc. can many of the extra functions be used on my car (apparently mine's a 03/91 car).

if this is too troublesome or if a lot of the features would end up being redundant, how hard is it to find a 7 button replacement. i've never seen any on ebay.