How long have you had the plant and how large is it, and do you feed it with anything? Where is the leaf loss coming from, is it all over or mostly from the bottom of the plant?
These plants hate draughts and sudden changes of temperature, need the compost to dry out slightly between waterings, but not be allowed to dry out completely, do not like direct sunlight nor heat sources close by. If you've had the plant for a while, have you moved it in the last few months?

Hi, I have had the tree now 20 years and it is about 2m high and I have always kept the tree in the conservatory which has no heating, the leaf loss is all over and I fed the tree with food sticks.

If you've not repotted it in a long time, it will need a larger pot and fresh compost - its certainly worth a try. If the roots are coiled round the rootball, straighten them out and rake the rootball lightly to get the roots pointing outwards before placing in new pot, and backfill with fresh compost.