Highest and Best Confusion

[Dee Powers]

I wrote and offer on a REO property. Banks says there were multiple offers, send your Highest and Best. I did....and my offer was accepted. Problem is...they finally sent the ratified contract and it's for the amount prior to my highest and best and includes closing which my highest and best didn't. Is this contract binding? Or can the bank come back and so oh no..we meant blah blah. The difference between this contract and my highest and best is about 20k.