Unable to view full screen from iPhone application!

I recently purchased a textbook and downloaded the Bookshelf application for convenient reading access from my iPhone 6s. Im extremely frustrated as the application will not allow me to view a full page. Instead, it cuts about a quarter of the page off leaving a large white block at the top of the screen. When I try to reposition the page onto the full-screen, I am unable. This means that I am completely unable to read a full-page in its proper context. Ive contacted customer service for assistance and hope that they will reach out soon as I have a limited amount of time to complete the reading of this text book. I paid a lot of money for this textbook and will be extremely frustrated if Im unable to read it.

Giraffe11223344 about Bookshelf