I couldn't figure out how to leave updated comments on eBay, but I did just open a dispute with PayPal...
Click on your feedback number and all your feedback should pop up.
On the bottom left (way down) underneath your page number see this:
What would you like to do next?
Leave Feedback...
If you paid with paypal, you can file a dispute and escalate it to a claim in which paypal decides if you get your money back or not.
You should certainly win if you did not get what you paid for.