I've been selling all sorts of things for months and it's all been fine, but last week I sold some boots and the buyer has been in touch to say the soles are covered in a glue type substance and I obviously knew this before posting them out 
She's sent a stream of mildly aggressive messages full of "???" and photos of the boots stuck together sole to sole saying they came out of the packaging like that (strange, since I did not package them up sole to sole). Now, as per eBay guidelines I have said I'll refund her if she returns them to me - and I need to refund both sets of postage, correct? - but she just responded with yet more photos and "these are unusable!" so I had to ask her again, are you happy to return them for a refund?
Now she's saying "I need to show them to my daughter and get back to you".
Now, my spidey senses are tingling because who would not accept a full refund in this situation? I just have this feeling she's going to pull a scam, so, wise people, can you advise? 