Why haven't I received my refund yet on ebay?

On the 7 th of September I bought a laptop on ebay. Unfortunately, I had to move from the address where the laptop was shipped so the seller wrote me that she will stop the package and will refund me. This happened like on the 15th of September and after that I keep writing her messages asking about the refund's date but she won't reply. She is from the States and has 98.9% postivie feedback. I am from the UK. Should I open a case on ebay and if yes is there a particular one for cases like mine? Thank you for your answer in advance! Attila