Your question is a legal question, and without a license to practice law, Realtors shouldn't give any legal advice. Consult an attorney. Common sense brings up questions like:
- What damage did you suffer?
- In what way was the lender negligent?
- Did the lender ask for the appraisal in a timely manner?
- Did the lender receive the appraisal in a timely manner?
- How much time was given in the contract for the lender to process this file?
- Did the person who wrote your contract include contingencies regarding the lending/appraisal, and the need for possible extensions?