I was told by the supplier to plant it in the shade but it has not made any new growth since June and doesn't look very happy. Hope you can help. Thanks.
It does need to go into shade, but not deep, deep shade. If it is in a mostly shady area, this is fine.
It may also be having root problems. If it suffered from transplant shock early on, or experienced dry weather while it was getting established, it may have root problems. Similarly, if the area where it is planted is very wet, this can also cause root problems.