In fairness to the developer, the MegaPack description does make it pretty clear this is NOT a word processing package or an Office suite package.
It is simply a bundle of document templates and is supposed to be compatible with either iWorks or MS Office - it does not replace either office suite or any app within in. It is just a collection of pre-formatted templates for documents.
That does not excuse the fact it may not be working as advertised, nor for the developer to hide from his coustomers. But if you failed to understand what you were buying, then you needed to pay closer attention to the app description in iTunes - the very first line of the App description makes it clear this is nothing more then a bundle of document templates for iWorks or MS Office.