It was getting really bad for a while, was getting 3-5 a day for a couple months last summer. It's calmed down since then. When it started becoming a daily thing and I just happen to be in front of the computer, I would stick my phone in front of the speaker and play this for them, very loudly.
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I got sick of doing that everyday, so I installed an app "Calls Blocker" from XDA and it's blocked pretty much all spam calls, and what does manage to get through Google Fi handles the rest by marking them as spam.