"by system via support "in our activity logs?

We have had two incidents whereby we see in our activity logs in our membership area that a gmail member's settings appear to have changed and it says in the log : "<xxxxxxx@gmail.com> by system via support".

The result is:

1- we cannot see these members in our member list anymore

2- they still receive digests

3- they cannot login in to groups.yahoo.com

4- the messages they send bounce (you can see that in activity logs)

5- they cannot unsubscribe via the unsubscribe email address and get a message saying they are not members of the group despite still receiving the digests and not having been removed or unsubscribed

6- If they create a new YAhoo! account and add their gmail as their alternate primary address the yahoo! profile won't accept it when they try to re-join our groups with that method.

The result is they can only join with either a new gmail or a new yahoo but we cannot remove their original email, they continue to get digests, and they can't unsubscribe or login.

Can you please advise?

Thank you so much for your hard work!