This probably isn't sufficient grounds for a refund, but you're welcome to take that up with IPS. They're out of my control. marketplace@invisionpower.com
An alternative approach would be to create blocks for your pages' header and footer, and then add those blocks above and below each page you create. You could put any content or HTML you want in those blocks, including those starting and ending tags. Either way, this app is about giving you the power and flexibility to do whatever you want -- that doesn't necessarily mean it'll be easy. Your specific issue seems like more a result of your theme to me, but I'm not going to argue the point.