What should I do if the client drops dog off without paying?

Hi, This is literally my second client- I'm learning A LOT from this no worries, there are many things I would not have done if I had the chance to do it again but as it is, I've made a mistake. I want to know what actions I can take, especially what would lead to me getting paid!

I accepted a last minute booking request Sunday night- Rover encourages us to take as many bookings as possible, and I wanted to build my client base. Client and the dog show up in a few hours for a meet and greet, it goes extremely well- the dog is very calm and sweet, I think it will be okay. So I tell the client to go ahead and confirm the booking on the spot. Client says they don't have enough money on the debit, so they need to go get cash from their spouse and then will pay tonight and suddenly they "have to be somewhere at 9:45" so they leave me with the dog. I was flustered and did not put my foot down enough (mistake I know). Anyway, it's the second day and the client is still full of excuses. I've sent follow ups, reminders, check-ins- all very polite like, "you mentioned you'd pay last night and I wanted to let you know the payment did not go through, can you do so at your earliest convenience? I want your pup to be covered by insurance so he's safe!" etc. Then I read on another post about sending a threat about Rover contacting me because they suspect I accept cash- THAT one gets me an answer from client in 2 minutes, client promises to deliver payment by end of day today. That has not happened yet, and it's 9:10 pm. I've sent another message.

What can I do to get paid?