Hi,
I have the same issue here. I didn't know I had a German version of the Galaxy S until this issue. (Product Code: I9000HKDDBT so it seems to be from Debitel, but I bought it through pixmania-pro.be)
The worst is that I didn't figure out Kies proposed me the version I already had, so I tried to upgrade… and the upgrade crashed! My Galaxy S didn't boot anymore… Fortunately Kies makes a full backup before the upgrade so I could switch the Galaxy S in rescue mode and restore it. I did this 5 times with different kinds of crashes (I think the last time it almost worked) before figuring out Kies was trying to "upgrade" to the version I already have

Now I use the Check Fus app to check for upgrade :
http://forum.xda-developers.com/showthread.php?t=834884(note that for the "Product code", this is also a code you must type in the phone app)
I am now considering to do a registry hack in order to switch to the European version, which is in 2.2.1…