Business being Harassed

Hello to everyone, I would need some advice on what legal actions can be taken to a customer who has been harassing me for the past 2 weeks. I am an owner of a small re-upholstery business which has been operating for almost 9 years. It’s a customer who contracted us to re-upholster her furniture. We have followed all the requests she has made and delivered it right on time. Upon delivery she complained about some details that were not mentioned in the agreement. Even so, we were never hesitant to accept her complaints and made arrangements to follow her demand. But the same thing happened when we delivered her set in the next few days. This scenario happened for 2 more occasions and now she’s harassing me that she will sue me because of her inconvenience which should not have happened if she only had not changed her mind upon the deliveries. I wish to know if I can take any actions to defend myself legally against my client. I would very much appreciate it if someone can help me in this dilemma. I am running an honest business and meant no harm to my customers.

Have her specifications in writing. Then do it.

Many thanks for the advise. I also wish to know if a case can be filed against me? Which she always mention whenever I try to communicate to settle the issue.