Disable Call Forwarding

I used to work for a Car Dealership who added me to their phone directory, and I haven’t worked for the company for a number of months but I keep getting calls routed to me. I have called a number of times to request they remove me from their directory and call forwarding, but the owner doesn’t seem to have an active brain cell that is capable of doing this simple task. I’ve resorted to telling people to try an entirely different dealership for help, solely outta sheer annoyance.

Anyone have any suggestions aside from changing my phone number, or changing my settings to “Silence Unknown Callers” / Junk filter? My phone isn’t showing the “Call Forwarding” choice either.

I have an iPhone 14 Pro Max, and have worked with cell phones extensively in the past (I worked for a couple cell phone companies).

Thank you!