I had allot of trouble when I first purchased my 607 3 years ago,it kept telling me I was in Paris,after changing the unit in the boot and half a dozen visits later,it worked out it was a bad earth.But to get it going they had to send for a setup disc that should of been with the car,they then ran that,then nav disc for the UK,everything ok.Hope this helps you out,Because I know how much it can p*ss you off,good luck.
Stenny
November 2007