I sold a top, described as used. I'd only worn it a couple of times, but have to confess I forgot to wash it (it was hanging in my wardrobe), it's black and could reasonably have had deodorant stains under the arms. The buyer contacted me 16 days after I sent it to say it was not as described and she wanted a refund. Is there a time limit for refunding or should I just refund and without grumble?