You are certainly not the first or the only seller having problems with that promotion.

On the current advice from ebay you will get your voucher....eventually!!!

Just don't hold your breath.

There was a similar problem with a buyer voucher at the same time....many of us did not get them and when we rang ebay we had to end up notifying them when we had spent the money with the promise of receiving the value of the voucher into our paypal account in 15-21 days.  I am still waiting.