Relentless daily spam calls

I have been recieving relentless spam calls from a number which constantly alternates its last two digits rendering blocking the number useless. It's either a robot call, a person asking for my name or simply a hang up. True caller identifies these numbers as from Discovery and the comments on the app confirms as much.

No matter how hard I try, I keep getting called. I am a discovery health client, therefore I guess that's where they got my information from, however, call centres obtain data via other dubious means.

How on earth can I get these calls to stop? I expect important calls, therefore I need to answer every incoming call, just to have Discovery bank calling me twice a day.

PLEASE STOP!