Buy yourselves a call blocker, or, a phone with a good call blocking facility. We havn't received any spam calls for months, and better still, they'll block a series of numbers that the spammers like to use.
I've had some fun with the theiving ****s in the past, like pretending to be Scotland yard, Bill Gates personal manager, Buckhingham palace press office etc...
World's your oyster if you're bored