Coming back to the dealer after a few days to specifically deal with the seat issue, I was better prepared this time. A quick google search showed that quite a number of people were having exactly the same issue with new Imprezas. In case anybody is interested, here’s the most useful link: http://forums.nasioc.com/forums/showthread.php?t=2358942
Talking to the dealer this time seemed to go better, with a different mechanic coming out to discuss the issues with me. Showing him the service bulletin from Subaru got him to (quite eagerly I must admit) agree that this issue should have been fixed at 6 months service and that the dealer would call me back in a few days (once they have all the necessary parts) to bring my car in to fix this.
“Yay!” I thought… a few more days of this frustration and then the seats will be awesome once again (like they should be on a 27 grand brand new car in the first place…)