Please check buyer feedback before sending anything as a protection for yourself and personally, I wouldn't have dealt with any buyer who had to be reminded to pay time and time again.

Actually, now that we have that additional info - what this sounds like is a buyer who realised she would get an unpaid item strike on her account if she didn't pay up, so she did, but now the return request is just a way for her recover her costs as she had changed her mind back when she was bidding on the dress originally. This way she doesn't get a defect.

Tell her you cannot assess any claim until you have a proper photo. Also, you can advise her that if the item arrives back in perfect condition, then it will be considered a change of mind situation and you will only refund the item prices less all the postage costs.