You've paid for a "perfect " example so that's what you should get.
I'd be reluctant to go through the rigmarole of returning it TBH so would negotiate with the seller - but a £30 voucher isn't negotiating in my mind - the cost of the courier is half that, somebody's time to arrange for collection, etc and they're almost even.
Refund may be the way to go if they don't want to be customer focused.