How to proceed with a cancelled dog walk?

I had six walks booked with a dog this weekend (3 in the morning and 3 at night). The lady said I could come to her apartment the morning of the first walk to get the key from her sister. When I got there her sister said that plans changed and she would actually be home to let the dog out, so they didn't need me anymore. I offered to cancel the walks but she said I could just keep it as is since I probably lost other walks because of it (which is true).

What would you do? Cancel, or let it ride? If I keep the walks and don't do them, how does that work? Do I still need to start "fake walks" to get paid?