Think about it. Bids have been placed based on the information in the listing. If you coud edit the listing then the bidders could find themselves buying something they don't want then you would really have a problem.
All you can edit is possible adding additional photos, or adding to the description, but it is below the line and would not be seen by existing bidders and probably not any other bidders.
If the reason for wanting to edit is something really serious then you would have to end the listing.
Speaking to ebay is just a waste of time they cannot change the rules.
