From what I've been told by a few lenders, they're swamped with defaulted mortgages and advise patience when calling about workout solutions.
Your offer is one of many and the lender will examine it as soon as possible. They say that it may take more than a week to examine the paperwork and come back with a response. If you state in your short sale request that a response is required within a certain time you may be doing yourself more harm than good. A statement that a response is required in no more than 48 hours may cause your request to be rejected.
For more information on loan workouts, visit www.ForeclosedDreams.com/foreclosure-workout-ideas.