Corp owned can take a while no matter what. They don't typically work evenings, weekends, holidays, etc. If you are asking for something outside of the assigned employee's preapproved guidelines (like a lower price) then it might have to go "higher up" or back to the client for approval.
Sometimes, now that the account manager has the file in front of them. However, don't expect much. They are the emotionless seller here. Bluffs don't usually work too well on the bank. Just hang in there, and don't be afraid to lean on your agent or theirs to get as much information as you can.
The other thing that I would add is that I have seen some of the best "deals" on corporate owned. Much better than foreclosures, which tend to be in less than perfect condition. So, while it may be nerve-wracking, you might be handsomely rewarded for a few extra days of waiting.