After listening to the radio in my partners Smart car (with the upgraded speaker pack) i have decided that the ones in the fabia just sound so flat! is there a speaker upgrade pack i can get from the dealer or does anyone know what size the door speakers are (Front and rear)?

This seems to be sadly common on the latest generation of Skodas, my brother has noticed the same on his 60 plate Superb 2 and is going to great lengths to rectify it. On my 2007 Octavia the sound system is very pleasing, I guess it's just VW sticking their teutonic cost saving oar in! Not that this helps you, just an observation.

They are 6.5 inch speakers in the front and rear doors. Tweeters are about 1 inch.