I answered calls from this number several times, listened to their pitch and then kindly asked them to stop calling. They don't stop. I have now blocked their number. It's 6:30pm right now. They've called six times in the last 5 hours.
Have blocked this number on my cell (so it does not ring or interrupt, but it does display a note of a blocked call). Have received calls almost every day for the past several weeks.
Called twice today so far, one hour apart. No message left. Luckily there are apps that "ignore" everyone who's not on my contacts list. If it was important, they'd leave a message.