One of the lads from the BXClub has now opened a Xantia forum which I think should be a well used place as there's still loads of Xants out there.
Have a look in and drop by and introduce yourselves if you get a minute...

http://xantia.ipbfree.com/index.php?act=idx

I've noticed a few Xantia Activa owners on here (I used to have one too ) - imagine all the problems that are possible on a hydractive 2 XM then add two hydraulic levelling rams, 3 more spheres and a more complex suspension computer into the mix! they're a dedicated bunch that hang out here-
http://s7.invisionfree.com/ActivaNet/index.php?act=idx