There are still rooms and suites available at the main Festival hotel at regular prices. These can be reserved calling the central or local reservations numbers.
The Renaissance also has a number of rooms available for the group rate for July 3rd. Please note that the combined choir concert and the Festival banquet and ball are on Monday, July 3rd. If you reservered a room with a departure date of July 3rd not realizing the schedule, you can still add that night for check-out July 4th until the block is sold out.
Use the website to make any changes or to cancel your reservation. The link is here.
Reservations can also be handled through the Marriott central reservations toll-free number 877-212-5752 or the local Baltimore number 410-547-1200.