Feeling harassed by Advantage Collection Professionals, anyone else?

Hi everyone, I’m dealing with something stressful and wanted to see if anyone here has been in the same situation. Advantage Collection Professionals has been contacting me nonstop about a debt that I honestly don’t think I owe anymore. I’ve gotten calls at all hours and multiple letters in the mail, and it’s starting to feel like harassment rather than just normal debt collection.

I came across this article that goes into detail about Advantage Collection Professionals debt collection harassment and what people can do about it: https://protectionforconsumers.com/advantage-collection-professionals-debt-collection-harassment/

Has anyone had to deal with them? What steps did you take to stop the calls and letters without making things worse? Any advice would really help because I’m feeling a bit overwhelmed.