Mortgage Refinance: 105 Days to Close and Overpaid Interest

[Vadimbr]

My question involves a mortgage in the state of: California

I received a letter from my current mortgage lender (one of the nationwide lenders) to refi my existing mortgage with them. On Sep 30 applied for a loan over the phone, paid application fee for 60 day rate lock with no points and no other escrow cost. Rate lock would expire on Nov 30, 2009.
However by that date lender was not able to complete underwriting. They extended the rate lock 5 times now with no additional cost to me (as it was no my fault for rate extension). Finally we are going to sign and close next week, after 105 days in transaction. I kept making payments to my current mortgage. If I would be able to close by the rate expiration date of 11-30-09, I would pay ~$700 less in interest for these 45 additional days since then.
I'm going to send a letter to the lender requesting interest refund, but frankly doubt that I would get any success. Anyone been in this situation? Any suggestions? Small claims court? Or something else? Thanks in advance!

[Mr. Knowitall]

Read your contract. It probably absolves them from any liability.