After discarding ficus in the past that shed its leaves I recently tried again and the leaves fell again after transfer from shop to home. This time I left it , continued to water as prescribed and all the leaves returned and its growing well. However I am reluctant to even move it from room to room in case it sulks.

These are prone to scale, which is difficult to get rid of. I used to scrape it off with a fingernail, but couldn't eliminate it completely. Spray misting helps but after eleven years I chucked ours out!

If the scale is on the woody stems, get some methylated spirits, moisten a disposable cloth lightly with it, then rub that over the scale to get them off. Don't get it on the leaves though, nor have the cloth wet enough to drip everywhere. Check the backs of the leaves though to see if there's any nymphs along the central rib - if there are, then you'd need a proper insecticide to spray with - not sure if neem oil works on scale, might do.

This particular Ficus is notoriously finicky, even indoors - a change of seasons, a draught, a change of position, lower or higher temperatures, all upset it, so it was always going to be shocked by its move, but it does look genuinely sick, which, if there's a heavy scale infestation, could be accounted for by that.

It's the wrong time of year to cut it back really hard, best done in spring, but if/when you do cut it back, either put it somewhere with a hard floor which can be cleaned afterwards, or put sheets of paper around it on the ground/floor - it bleeds like mad when cut. After cutting back, keep it fed with a balanced fertiliser, and watered as necessary, find a position where it's not exposed to a heat source, strong direct sunlight, or draughts.