“You can’t just hang up the phone on them”
Yes you can. Try it. You’ll be amazed. I’m not saying you should just slam down the phone. What I am saying is, if you say you are not interested and they continue to go on and on, politely say, I said no and I will hang up in 5 seconds. After that, they have the option to say ok, or go on and on and be hung up on.