For a smart phone a call blocker is an ap. There might be one pre-installed on your phone or you can download a free one.
For a simple cell phone ask your carrier. Or put the pest in your contacts list - I name mine X - and give them the ring tone "no ring" or "silence". That won't stop the calls but it will make them easier to ignore.
Has started calling here. But our call blocker data base has the number they are using and blocks the number. Not sure who actually answers calls from survey companies and that is probably why most surveys these days are unreliable.