I hope your home sale went well or is still going well. With 8 days, that SHOULD be plenty of time to postpone a sale date but it depends on the bank, the new offer price/terms, and your agent's persistence. I don't see why they wouldn't postpone the sale date based on what you told me but if they didn't probably one of the following occured:
1. the new offer price/terms was not even close to what they would accept and they rejected it outright to move forward with foreclosure.
2. the lender postponed the short sale BUT the listing agent did not follow up enough or check with the trustee to ensure it was postponed.
3. the lender did not get the order to stop/postpone the sale to the trustee in time before the sale occured.
I hope none of the three above occurred.