Is Pressler and Pressler calling anyone else nonstop? Feeling harassed.

I've been getting constant calls from Pressler and Pressler for a few weeks now, sometimes as early as 7:30 AM and as late as 9:30 PM. They’ve even called my workplace a couple of times even though I asked them not to. The caller is rude and keeps threatening to sue me if I don't pay immediately.

From what I’ve read online, like on this page, some of this might actually be illegal harassment under the Fair Debt Collection Practices Act (FDCPA). Things like calling outside allowed hours, contacting me at work after being told to stop, and making threats.

Has anyone else dealt with this kind of behavior from them? What did you do to make it stop? I'm considering sending a formal cease-and-desist letter or filing a complaint. Any advice would be really appreciated.