What's the panic about? Give it a few days. If CO said it was processed on the 23rd - and the 24th and 25th are reduced/zero business days - then take into account the holiday period. You already have CO's promise to refund the payment....what other possible outcome would disputing the credit card charge get you?

The first thing the credit card company asks when you dispute a charge is "have you tried to work this out with the merchant already?" And your response would be "yes, they've agreed to refund my money."