Inform the owners of those banned accounts of the reason(s) for being banned. Don't keep them blinded of your "banning" wave reasons - I assume that the ban wave was system generated. Moving forward, give them opportunity to explain and reason out if the "reasons" are true or not - assuming that the bad wave was system generated, at least it will be fixed by manually checking it.
Those who will be able to explain and prove that they're clean, unban them. Maybe it would take too long, but at least legit players will be unbanned.
