Welcome @jmchampson sorry that you find yourself in this situation. It must be very stressful.
After you confirmed the sitter did they accept - is it showing on your dashboard ?
You can ask member service to contact the sitter on your behalf . They have contact phone numbers etc .
E-mail support@trustedhousesitters.com Titling it asURGENT or use live chat and ask to speak to a human ( not the chatbot Frankie )
Please let us know how you get on and these threads my give you some hope .