What to do when Owner is picking up dog one day late and has not accepted the extended stay request?

Owner was supposed to pick up yesterday. He let me know after 11pm that someone else would be picking up the dog this afternoon. I sent a request today to extended the stay for one more day but he has not responded to it or accepted it. What should I do when this other person shows up to get the dog but the owner still has not paid for the extra day? Thanks