I'm so sorry this has happened, that quilter should be thoroughly ashamed of herself for doing this to you! She owes you a refund for part if not all of the price she charged you!
You can have the quilt finished by another Longarmer who can create a leaf pattern from those that are already on the quilt. If you try and finish on your domestic machine, there is no way it is going to come close to looking similar, especially as you are new at it.