eBay neither monitor nor respond to the boards, regardless of what the board header says.
Any response you will get is from other members, who have no more power than you to fix things.
RING eBay and hope you can sort it out.
As a general observation -
Place items in cart,
Apply discount code.
If the code works, pay.
If it doesn't, don't pay.
That way you are not hoping for a dispensation from eBay.
The 7% promo is for selected sellers. Are you sure your seller was selected?
