I understand your frustration. It seems like it should be so simple, shouldn't it?! I always tell my clients to remember that the banks are not emotionally involved in the transaction, have never seen the home and have never met you as the client. There is not a lot of motivation on their end to sell quickly. It can take weeks to 4 months to recieve an answer on the purchase agreement that you submitted on a short sale.
Most buyers get frustrated waiting and see other homes of interest while they are waiting to hear back and tend to go in another direction. Good luck with the waiting it out process. I wish you the best!
All banks pretty much take their own time to get back to offers regardless of how motivated they may be. Remember, they have thousands of homes in foreclosure and short sale, and when you respond, you're in the que behind all the other offers. When your file pops up as the next to handle, that's when they get to it. It's frustrating I know, but having handled many I can tell you that's the way it works. Just be patient or cancel the offer and move on. Those are really your options.
Seriously, they can be a bit difficult to work with. I tell my clients 2 weeks to 3 months. The listing agent (if they have worked with countrywide before) should be able to give you a rough estimate. Of course that is just an estimate. I hope it works out. Sometimes the wait can be well worth it! Good Luck!