If you are using a courier company worth being called a courier they should not accept a parcel for delivery to an area they do not deliver to.

If you are going to use just one courier company you need to find one that guarantees door to door delivery to all areas....which means one of the larger companies like Toll or StarTrack.   If they do not deliver to an area but accept deliveries to that area you usually find they have an arrangement with a local company complete the delivery.

The only problem with that is that the larger companies do not deal with small volume clients.  You would have to use a courier broker like Temando to access the larger companies