Changing a Sender's SenderStatus

I have inherited a small (and incomplete) application from a former developer at my company that uses v11.5 of the .Net SDK to manage senders for our account. Recently we used the app to delete a sender via a call to AccountService.DeleteSender(). This call didn’t remove the sender; it changed the sender’s Status from SenderStatus.ACTIVE to SenderStatus.LOCKED. Seemed reasonable at the time, and it had the desired effect. Now we need to re-activate this sender, and I must update our application to perform this operation. However, I can’t find any method in the SDK (or an example in the forums) to update a sender’s Status back to ACTIVE. Do I need to simply re-invite the user via a call to AccountService.SendInvite? If not, please advise as to the proper method for getting this user back to an active state.