So does the lock work with the key on drivers side so it unoocks without any electrical help namely central locking, so the drivers door can be opened, just not anyothers?
Changing immo parts arent as easy as it would seem, you need the skc which is your security pin & you need to possibly recode the cluster & all the keys to the car at the same time, you need someone local to you whose prepared to scan the car with VCDS, where abouts are you.
I need to have a look at the A6 04 wiring/parts diagrams to check what systems it uses.
Also try not to edit your previous messages mate & delete the whole message, add any info you forgot or correct any info, but add new messages for replies, cause others then cant read the whole problem if you continually delete info, if you can then try to return the original post to what it was then it helps others with same problems.