It seems you solved your issue already. Muting. What more can be done? This is all under a suspicion of foul play. As far as I am concerned or ethical standards, being under suspicion is not abuse.

Need something more concrete than what is shown here.

If the front end is yours you can mark any user you like that you suspect as suspicious for all to see and link your reasons for each one.

And maybe people will just not vote for it.

These are the 3 or 4 votes, Do You think it's organic?

And if it's automatic?

When I muted them so MOD of my community Miss Fabiha un-ban the @samantharac account without my permission.

If it's a community account and you gave them access to it, technically you gave them permission unless you have some sort of agreement that is not being made clear between the two of you, that may need to be addressed. Are you the only one allowed to ban and unban?