My realtor comped my house wrong!

[Brandon Woodall]

SO... Realtor comped my house as a single level at 1700 sq ft, but its a split level that is a finished basement. Which the appraiser is saying should've been comped way different. So the realtor came up with $215,000 but we decided to list it at $193,000 thinking we should be good. So i take an offer of $193,000 and I pay closing costs, plus some repairs totaling around $2500. Do the repairs and get the appraisal done, they point out its been comped wrong and that it barely appraises at $170,000, 2 wks before closing... Real estate agent says oops, and thats it. Now were going to have to renegotiate and with the terms we have I'll be in the negative and end up owing money out of pocket. What can I do??? Anything? What are my options? Anyone with any insight would be much appreciated!