Hey guys thank you for your response. I am using WP Invoicing plugin for the payment processing. The code I am using is somewhat like this: (package id: 5 is the premium package)
<?php
if(isset($_POST['submit'])){
if($_POST['package'] == "5"){
$post = get_post($_POST['listingid']);
//proceed to wp invoicing adding to cart and forward to the payment gateway
}
}
//global $wpdb;
//$sql = $wpdb->get_results("Update {$wpdb->prefix}geodir_gd_coach_detail set package_id=5 WHERE ");
?>
<form method="post" action="" name="updatePackage">
Please select a package
<br>
<br>
<input type="radio" name="package" value="1" checked> Free
<input type="radio" name="package" value="5"> Premium
<input type="hidden" name="listingid" value="<?php print $listingid?>">
<br>
<br>
<br>
<input type="submit" name="submit">
</form>