What is my liability if I walk away from a refinance at the closing table?

Decided it was time to refinance my mortgage. Shopped rates and picked an offer, then jumped through all the hoops of getting the home appraised, providing all of the documentation the lender needed, etc. Whole process was really smooth until we are cleared to close, then the person in charge of coordinating our closing has dropped the ball completely.

We were originally scheduled to close on Oct. 6th (13 days ago as of this writing), but when I got the closing disclosure the afternoon before there were some items I had questions on (one new charge, and one grossly incorrect amount). I reached out to the notary and lender, but didn’t get a response in time, so the notary did not show (at my house) for the closing. Now the lender’s rep is basically AWOL – I’ve gotten a couple of messages from her saying that she will call me soon, or that we can schedule to close around date X, but then there’s no follow through on the promises and no explanation as to why.

On the lender’s website I found a ‘Complaints’ department, so I reached out to them. Rep seemed helpful at first, but hasn’t been able to get any movement in over a week, so I’m losing confidence in that route.

At this point, I have paid $550 to the lender as a "deposit", which was the estimated ceiling for the cost of the appriasal. I’ve been told that the actual cost was $450, and that the $100 extra will be refunded after closing. No other payments to them or any other parties for the refinance to date.

I’m trying to assess the costs of starting over with a new lender. If I walk away from the loan at this point, what is my liability to the original lender? Will I owe money for any of the additional third party services that they have obtained during the application process (title research, HOA documents, etc.)? Do I have any way to get back any of the $550 deposit that I put down, and/or can I take the same appraisal report to a different lender and have any chance they will accept it for a refinance?