Timing belts

Hello I have many questions. 1.) My KIA PICANTO EX 1.1 48KW (65hp) BAUJA 12/2006 so soon 6 years old. But has only 13200 KM.(So no 3000 KM per year.) In my operating instructions it is necessary to change the timing belt at 90000 KM or 6 years. Is this necessary with my very low mileage. The workshop would say : 6 years change,so!! 2.)How can you look at this? 3.) What can the cost of changing the timing belt? Would I be pleased with the answers. Gerd