Contractor acting as their own collections agent?

Again, crazy contractor claims I owe her money and she says she can call me up to 5 times a day to just harass me into paying. She is trying to support her actions by claiming that "she does collections too" and that she can call me up to 5 times per day legally. What can I do to avert this? Can I bring a lawyer into this action for Fair Collections laws? And can she call me this me times per day without any consequences?