Wordpress Plugin Modification - Facebook Like for Woocommerce free gift

We currently have purchased this plugin: [login to view URL] which gives a customer a free gift based on total amount in the woo commerce shopping cart. We would like it modified to offer customer a free gift only after liking our Facebook page. 1. User should be shown a like button at checkout, with message text that is editable in the Backend. e.g. "Like our page to receive a free gift" 2. Like button should be hidden after user selects 'like' and message should appear, "Thanks for liking our page" allowing customer to select free gift. 3. User should always be offered to select free gift whenever they are purchasing from the store if they still currently like the page. 4. If user has unliked the page they will be prompted to like again to receive free gift thanks!