With hundreds of millions of bids every day, it would not be surprising to learn that eBay gets tens of thousands of complaints every day. Since the role of eBay is that of an auction house, responding to run-of-the-mill complaints like "this jerk dissed me!" is likely to take a low priority in eBay's scheme of things. Accordingly, while eBay does indeed have a staff of people that looks into complaints, that staff is probably very small in numbers and highly overworked.
This is not to say that complaints should not be addressed. However, it's beyond praying for that most complaints will receive prompt attention. If you're careful in your wording of a complaint, you can probably catch the eye of someone on that overworked staff: words like "mail fraud" or "obscenities" probably gather attention before more mundane vocabulary does.