Please contact our customer service. They will take your request and forward it to our construction department. If the plans are available, we will send them to you. Otherwise they will tell you where you can get the plans.
Regarding the right of access. When you bought the house, you acquired the right of access. You can see exactly how this looks like in your purchase documents. In principle, the technicians should give you a short message when they have to work on the box.