You should try the Brodit Pro Clips and mounts. They fit inbetween the trim on the dash
http://www.dsldevelopments.com/brodit/Brodit Proclip.asp
Search for the Ibiza on the link above, and you can find the clip. Then you can buy mounts which slide onto the clips
what headunit u got? i got a ipod capable unit and dont know if my phone works with it, was gonna try get the ipod cable in later today!
Yup, you really gotta make sure it's iPhone 3G compatible, not just iPhone (If you've got the 3G anyways.) as they changed the pins slightly I think. I think one of the reasons most don't work is because it uses the 5V Data cable on the USB as well, not just the 12V line to charge it.
I use an Alpine CDE-104BTi and it works fully with my iPhone 3G, both the bluetooth Parrot part and the playing.