If you receive a new booking and upon reading the description you feel you are unable to help the client then please do contact them, or cancel the appointment.
When you recieve a new booking you are provided with the contact details for the client who has booked the appointment. Please do use these to discuss the situation with the client and if there is a better alternative solution for the client, then please advise them.
Either the client or you can cancel the booking to ensure the client does not get charged.