JRG1

ok,ive not long bought a discovery td5 automatic. this is the first automatic ive had so its taking a bit of getting used to. the problem im having is that it seems to hold on to 3rd for a long time before it changes up into 4th,it seems like wherever i go im mostly in 3rd which is doing my head right in. so, the question is,am i doing something wrong with the throttle, is it the way im driving or is there something wrong with the box?????

any help much appreciatted

cheeRS