im bit confused,i sold 3 items to the same person,had excellent feedback,now theres a case open,buyers says she hasnt opened a case

i sold 3 items to the same person,i even held an item for few days for her to bid on more,i gave her a refund for some p&p as well,now there`s a case open against me,even though she left me excellent feedback,the buyer says its a misunderstanding,she has`nt opened a case,but it`s been 3 days now since they took my payment of me and still no joy,what can i do