Dear sir,
I am sorry about missing your calls for several times. As the new system had been released online, there came out a lot of unexpected problems which were hardly handled.
I've skimmed over the business introduction that you mentioned and found some parts of which were not clear enough. Therefore I couldn't figure out how to operate this project or wether we need to enlarge the scale of our staff. From this point of view, I wish you could revise the introduction as soon as possible in order that I might give you a certain reply after reportting the issue to my boss.
Best regards.