I am looking at getting a bluetooth kit in my car (Parrot etc), but looking at the dash there is no way to have one fitted without it being really obvious, so has anybody taken out the standard Swing unit and replaced it with a double din unit that looks very OEM but has bluetooth already incl in it so calls etc can be made from there and thus  no need for another bit of kit ?

You can get the Amundsen+ which is the factory sat nav for the fabia. Some models have built in bluetoothe. Probably your best bet. If not you can have the factory bluetoothe system retro fitted I believe.