Why are my customers being redirected to the home page when they click on customize order button when using internet explorer?

If you are running your site in a frame, Internet Explorer finds it difficult to decipher the query and hence it redirects the user to the product page when you click on the “Customize Order" button. This is a limitation of Internet Explorer, and not eDocBuilder.
What happens is, when you click on the “Customize Order" button, the URL is pointing to your server, here you have an HTML page with i-frame that is pulling a Pressero page. 
In order to rectify this you can transfer your Domain to Pressero servers then it will reference to the real site not a link via i-frame  and this will resolve the issue or you can request your users to use Google Chrome.