Complex sentence: Poor management and a lack of communication between departments resulted in costs spiraling unchecked--the effectiveness of an eye-catching (and expensive) ad campaign was limited because the website wasn't ready in time, resulting in curious visitors being greeted with a holding page.
Split into simpler sentences: Poor management and a lack of communication between departments resulted in rapid growth in costs. The effectiveness of an expensive ad campaign was limited because the website wasn't ready in time, resulting in curious visitors being greeted with a holding page.