What Does It Take To Get PCGS To Correct Their Errors?

diehl

In the populations for the 2020, MS, Washington America the Beautiful Quarters, you will notice that there are already populations for all 5 "S" varieties. That is a good trick since these MS69 and MS70 quarters have been listed since before they were even released (some still haven't been released). Not to mention they are all MS69's and MS70's.
I suspect some unknowing employee thought the Clad Proof 2020-S were regular strikes.

I've tried repeatedly to get them removed with no luck.

ReadyFireAim

You might try on the registry set forum.
They have always been really fast to correct things when I post them there.

ms70

Send a PM to the Set Registry Manager:

https://forums.collectors.com/profile/SetRegistryManager