No. There's no way to speed up the bank. Really. No way.
The best you can do is to have your agent stay in regular contact with the listing agent to make sure that the seller is promptly responding to any and all requests from the lender. Lots of times, lenders repeatedly lose (or at least request) the same information over and over and over. It's essential for the seller to promptly respond to those repeated, increasingly annoying, requests.
You might share a few choice words with your agent who presumably knew of your timeline and apparently assured you that things would work out. Anyone who says they know with certainty how long a short sale will take is, umm, stretching the truth.
Again, make sure your agent is staying on top of everything. That's the best you can do.