MzTee, assuming you are correct and your dog is only barking a couple of times a day (and not one or twice a day for a half hour at a time), it sounds like your neighbour is being unreasonable. I believe the expectation is that a dog should not be annoying rather than completely silent. You should check that your dog is not barking while no one is at home to hear. You can do this easily by setting up your computer to record while you are out. There are some good free programs available for this such as Audacity. Then once you have all your ducks in a row, respond to the OC’s letter, indicating that it is not your dog making noise. I would not directly engage with her anymore if she is being abusive.