Thank you for your stay Nancy, and for sharing your comments here on Tripadvisor. We would like an opportunity to investigate your issue a bit further. When a group is confirmed, with a group code, the rates are locked in as long as bookings are made within a certain period of time (called the cutoff date). If booking after the agreed, and contracted, cutoff dates, rates could be higher as the new booking would not be made as part of the group.
If you are willing to discuss this further, so we can see exactly what occurred with this group, please call the hotel and ask to speak with the General Manager.