hello, having bit of a dilemma with a recent sale. was selling a designer brand that i purchased from an authorised reseller in the united states, buyer received item and wants a refund as she thinks it might not be authentic. i'm not really fussed on the details as i have original receipts from the original store, and could be a year/make/production difference or whatever she noticed.    she wants to return item, which i have agreed, however she is adamant she wants me to refund her before she sends the item back first. how should i approach this?