The John Deere's I have been working on are older and didn't have a timing belt. This is the first time I have hear of such a thing, but I do see a timing belt in the parts manual. What are the timing belts doing slipping or breaking? I would say not knowing the tractor, that you have a mechanic problem not a mower problem. I don't know about Scotland but in the US any dealer that amounts to anything will stand behind its repairs.