Trying to purchase pro pack – error on site

This error on your checkout page:

Warning: Missing argument 2 for wpdb::prepare() in /home/charlesu/public_html/wp-includes/wp-db.php on line 990
{"result":"success","redirect":"http:\/\/www.charlestonsw.com\/products\/checkout\/pay\/?key=order_50ce96b84e681&order=6632"}

Would like to purchase your product ??

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