Spam FaceTime Calls

There is a group of spammers that have been FaceTiming me for months and it is unending. A lot of times they’ll call me non stop for 20 to 30 minutes. I’ve picked up twice and both times it was kids. It’s mostly people using iCloud accounts to call, but also phone numbers. From what I can tell there’s no way to block FaceTime calls, because even though I have them all blocked, their calls come through every time. It’s incredibly frustrating, and the only option I have is to put my phone on do not disturb whenever they start calling, which I can’t do most of the time because I still need to get my other notifications.