Hi Ant.
just sharing one of my early learning experiences here. I sold an item and received an email saying it didn't work, the previous 40 I sold to other people worked fine. I emailed back with apologies and offered a full refund when they returned it. After waiting 9 days I thought oh well, it will arrive eventually and sent the refund. Naive or what !! needless to say, it never arrived. Maybe it was lost in the post -or maybe I'd been scammed. I will never know. I've moved on since then.