Closings and Escrow: Foreclosure- Back Taxes

My question involves real estate located in the State of: Vermont We are closing on Monday for a foreclosure. We are responsible for the back taxes. On the flyer the auction company posted the taxes as being $2,329.68 . good through 4/15/16. we are closing on 3/28/16. They now say the taxes are $3031.56, due to interest and penalty's. This is our first foreclosure purchase and understand it is our responsibility. We feel the auction company, in business for 50 + years have some responsibility. Opinions? Thank You

Closings and Escrow: Foreclosure- Back Taxes