Jaguar sat nav displaying 'disk error'?

Hi We have a XKR 2003 Jaguar, the sat nav displays 'disk error'. The car was purchased with no disks, we have purchased the Jaguar disk from ebay for 2003 & 2004, but both do not work. After talking to the Jaguar garage they what us to purchased their disks for £260.00 plus labour £200ish, but these new disks are out of date by afew years. After seeing what happens with their disks, they will check the system. The ebay seller is saying the disks should work as they are actual Jaguar disks & it must be the system. Can anyone help?