Pro site is sending payment confirmation when no payment is made. i tested it locally and live, am still getting the same thing. when user select a plan,and reach on paypal to pay if the user just click on cancel then it return a confirmation email that says " thank you for becoming a pro site member" and it automatically updated the site level even though no payment was made. please check it out ASAP.
Support is granted, test it using the ecom.thesitename.com blog.