start off with lockin her away an just standing in garden, talking to neighbours or wife or anything, let the dog hear ye an know ye are there, once ye feel she has got to the point where she will relax again, try it for longer, then maybe try it further away stop the taalking tho only make it short durations where yous are separated, then just build up from there,
i had to do it a few years ago with a dog that was about 13 months old before she ever really had to be left alone, an by 15 months she would happily spend a few hours on her own, an ended up a very easy dog to live with an lea