I purchased an Audi a3 1.8T Sport 1998 (R reg) but it only came with a single flat blade non-remote key. I know the alarm works but the drivers door does not unlock (key doesn't turn) so i have to unlock the car on the passenger side everytime i want to get in. 
is there any way I can either a) replace the key with a proper Audi flip remote key or b) add a universal or other remote central locking system but keep the functionality of the alarm?

any help would be greatly appreciated. 

thanks

had same problem on my a3. Got key fob and installed new elctrical  centeral locking, mostly effort having to remove door and panels but worth it. Have you had a look at drivers door lock?

My daughter had the same trouble with her Ford Ka. I fixed it with a little powdered graphite from a small squeezy bottle with the unlikely name of "Just a Puff".

I kid you not!