2003 Jaguar XJ8 Noises

2003 XJ8 when you are driving it sounds like something ratteling under the rear of the car. This only happens when you go over a bump or rough road. They re-shimed the wheel barring and this did no good. Also, there is another noise coming from the right rear that sounds like a tire rubbing on something metal. This happens only sometime and when you let off the gas peddle, sometime it quits and sometime it does not. Just bought this car and the local jag dealer will not even return my calls. Any help will be greatfully appreciated.
Thanks,
W.C. Staley
wcs615@aol. Com