You had an amount in mind at first, sort of a going-rate fee?
I would deduct the cost of the replaced items, and also consider things like unreplenished litter possibly and if she didn't visit as many times as she said she would. This might be hard to judge but I'm assuming if you know she didn't interact with them that you had a camera or two in place? Anyway, that's my thinking. If you're able to get her paid, you can then move forward a little more easily.
I would deduct the cost of the replaced items, and also consider things like unreplenished litter possibly and if she didn't visit as many times as she said she would. This might be hard to judge but I'm assuming if you know she didn't interact with them that you had a camera or two in place? Anyway, that's my thinking. If you're able to get her paid, you can then move forward a little more easily.