This exactly happen to my X-Type, at that time I was new to Jag and have not found Jag. Forum. I thought all coolants are the same, I refill with green coolant it star get over heat and lost coolant, saw no poodle, the gunk clogged up the coolant passage, it can't leak out so it have to leak in, break head gasket, finally kill the engine, so you must flush the coolant and fill back in with Dexcool immediately before do further damage to your engine. Tell your be love mechanic do it thoroughly and on his time and money.

 

It would be nice if the OP closed the thread out. I would have sued personally, but at the very least have them make it whole again.