Plugin not passing information to PayPal

I've set up this plugin to handle appointments for a client here:

Can you take a look at that page real quick? Choose an appointment and then look at the button at the bottom of the page - it doesn't refresh with the correct price or service name. Also, if clicked, that button leads to a PayPal payment page with a product just called SERVICE and a price of $0.00. Can you help me figure out why it's not working?