Failing central locking systems are a common S-Type fault, often caused by a failed sensor or lock. The rear window that's stuck open could be caused by a blown motor. With this age of car, it's always cheapest to do the work yourself if you can. That said, neither of these problems are unique to Jaguars and could both be sorted by a competent independent garage. Have a look at our Good Garage Guide (good-garage-guide.honestjohn.co.uk/) if you need to find a decent garage close to you.