I want my refund please.

I bought a product on Nike.com in December 2017 and never received the item because according to the Aramex courier company the car was hijacked & my item ******. I communicated this with Nike on Chat, Email and over the phone. I still don't have my refund nor the product...all they send is automated emails about "we are still working on it"....what MUST I do?? #Nike