RepairPal Certified shops can diagnose and repair your 2003 Jaguar S-Type. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
Have you checked to see if a under the hood light is on or a cell charger is shorting out. Might be a cell charger has a light that stays on. I had a radar detector that would drain the battery over night.