Castle Used Cars Inc review: backed out of written sales offer

On Saturday Jan 31, we were looking at a used 2007 Mercedes E350 at Castle used cars in Silver Spring Maryland. The sales manager on duty Andre Turner gave us a signed offer sheet with a price of $25000 and a $1500 trade-in allowance, for a net price of $23500. It was getting late, so we asked if we could come the next day. Andre promised the offer would still be valid. When I came back to complete the deal the next day, the owner refused to honor the offer and wanted $4000 more -- $29000. When I showed the general manager the signed offer sheet and told them I had driven over a half hour to get there, he did not care -- too bad. Gotta love their slogan -- "no Hassle at Castle". I have contacted an attorney to pursue this further. Given Catle managment's attitude, I'm not sure this will lead anywhere good, but I am very angry at how they jerked me around.