Not checking a contract for editions is your own fault - its not ethical, true, but it happens so often. The trick many lawyers do is just to compare where the punctuation occurs on the page at the end of each paragraph as it is just about impossible to change things and maintain the punctuation position.
And then if you signed it....well. Unless you have clear documentation like e-mails as to your intent or mark-ups of the contract that you have made and sent over. You need to take advice as, prima facie, you are exposed.