Revision or deletion of feedback

[gamclau96]

I sold an item, a collection of coins, which I received no notification due to turning off all notifications for apps on my phone. 

I sent the coins at no cost to the buyer in return for revised negative feedback.

The buyer nor I can update the negative feedback and now not only an I out the cost if postage and the full price for the coins, I can't remove their negative feedback!!

Please advise!!

Gavin

[plpmr]

unfortunately the neg is too old to revise.