If you have a paid listing on the site and a competing paid ad link appears on your page contact to inform the site administrator. The ad URL will be placed on a list of URL's that cannot appear on the site.

Even though the Paypal payments page appears on a page in this site, your payment is actually being made on the secure PayPal site. 

You can tell by the closed lock symbol on the bottom of the browser. Your credit card information is protected by encryption which scrambles the information as it is being processed by the PayPal site.