Is there a way I can block a client?

A few weeks ago I had a request to walk a client's dog, which I accepted. The walk was scheduled for 9:00 am, but she ended up being a no-show. She lived in an apartment building so I couldn't knock on her door, and I continued to message her asking where she was for over 20 minutes until it became obvious she wasn't coming out - so I left. Now, 3 weeks later, she has messaged me asking if she was charged for the dog walking. I said yes, because clients pay in advance, and she didn't actually even cancel the booking, she just didn't show up. She then asked me to walk her dog this week for free, to "make up for the walk she didn't get last time." I said that wasn't possible because why should I pencil her in to my schedule and take the time to drive to her home twice, only to get paid once. Now she's trying to tell me how to run my business from her experience working for a housekeeping business and that I shouldn't "send clients away for pennies". I know she's just bitter because she lost money and didn't get her dog walked and the only person to blame is her, but I really would not like for her to be able to message me or try to request bookings with me anymore. Is there a way that I can block her?