I sold a small bundle (4 items) of girls clothes. All in perfect condition I got 99p. Fair dos. Buyer now contacted me to ask what I was going to do about stains on the knee of some white trousers. There are no stains, I washed and ironed and photographed these, packed them up - no stains that I ever noticed. I wrote back and apologised and offered her a full refund if she sent the bundle back. She's said there's only a problem with the trousers. Shall I offer a partial refund? What would you do?