How I can get refund from Ring?

I returned "Spotlight Cam Battery with Free Solar Panel" this product one month age, and the package the package has reached the return address for more than 3 weeks. The RMA number is 2012215112. What makes me angry is that I have contacted customer service 4 times, and they always let me wait for a reply from the billing department but I never got any reply. I suspect they don’t have this department at all. Can anyone tell me how to get the refund from the ring? Thank you so much