This is a rant and I probably should delete it.

[TwilightZone]

7. A few suggestions:

It's already illegal to call at 5:00am. Those calls can be reported to the FTC (#2 below) and/or the FCC (#5 below).

1) Make sure that your client is on the Do-Not-Call list. If unsure, you can check (or apply) here:
https://www.donotcall.gov/

2) You can report unwanted calls to the FTC.
https://www.donotcall.gov/report.html

They do follow-up on reports, but it may take multiple reports about the same organization for them to take action and you likely won't receive any correspondence about outcomes, etc.

3) If the client has a VOIP landline (phone through internet, cable company, etc.), sign them up for Nomorobo. It's free for VOIP landlines:
https://www.nomorobo.com/

4) Many phone providers have blocking available and it's often as simple as dialing a code (*68, for example) after receiving a spam call.

The problem, of course, is that the same organization may call from multiple numbers, so it may be necessary to block a few before seeing some progress.

#3 and #4 made a huge difference for us.

5) The FCC also provides a Consumer Guide with resources, etc., on their website:

https://www.fcc.gov/sites/default/files/stop_unwanted_robocalls_and_texts.pdf