How can I handle harassment and defamation from a neighboring shop?

I have a small salon business, and recently I put a signboard on my wall. The lady from the shop next door is creating issues, saying it is blocking her display. I have evidence that my small board is not causing any hindrance, and she is unnecessarily creating these issues. She is posting on social media with my name and putting it down. She is constantly harassing me personally too and threatening me to remove my small board.