This is a message board for discussing spam and scam phone calls. Your pest does not own this message board and probably does not read here.
You need a call blocker. For a smart phone a call blocker is an app that may come with the phone or you can download a free one. For a land line phone a call blocker is an electronic box you can buy on line or at Best Buy.
For a simple cell phone ask your carrier. Or put the pest in your contacts list and give it the ring tone "no ring" or "silence". That won't stop the calls but it will make them easier to ignore.