2001 Land Rover Freelander

Hi. I brought a landrover freelander (2001) 12 months ago, and its been in the garage 3 times since. I brought it from a dealer and it is still on finance. After just 1500 miles, the cam belt snapped. The garage fixed that, but 4000 miles later, the head gasket and cylinder head have gone again due to a blockage in the radiator. I have contacted the finance company who say that for anything to be done about it, I have to prove that the problem with the cam belt was there when I brought it. I have a servive schedule which says that the cam belt should have been changed when the car was 6 years old. Having no service history, I dont know if this was done. If it was, do you think a cam belt would last longer than 13 months? If it wasn't done, then should the dealer have replaced it prior to me purchasing it? Also, is there any way to tell that the cam belt is going to snap 1500 miles before it does?