Perhaps message the owner something along the lines of, ' sorry we weren't able to meet up this time. Feel free to contact me should you need a sitter in the future.' If you're fairly new to Rover & wanting to build your clientele I would give the owner an second chance if/when the contact you again. If you're booked fairly regularly I would not hesitate to decline their requests - no explanation needed. When you archive any requests from them I would mark it "Owner not a good fit".

Per client request, I added 1 day at the beginning of a stay that is coming up tomorrow. Client says she's being charged for the entire stay again

I have had this same situation come up a few times. I am lucky enough to have mud-room off of the kitchen, with a gate, that I use to separate the guest furbaby from the Meet & Greet dogs. I've also, on occasion, blocked them in a bathroom, with the door open so they can see what's going on, but access is restricted by a baby-gate.

First make sure his/her ears are clean. Moisten a cotton ball with warm water and a bit of hydrogen peroxide or canine ear cleaner, gently wipe out the ears. Try clapping loudly when your pup is not looking at you. Does the dog react to whistling? Loud noises? Ask your vet to perform a BAER test.

Client Booked a Meet & Greet but messaged a few days prior to cancel since her brother was now able to watch the dog. How do I cancel the request, or do I even need to?