If someone is contacting me that I don't want to talk to or don't like I change their name in my phone to something that reminds me - like my former business associate for example. His name became "addict thief". My ex I changed to "pathogical liar". Believe it or not this is very effective as far as squelching the curiosity for why they called.
Eventually they stop calling when you don't answer or will text you what they want and you can decide if it merits response or not.