Refused to refund my core charge because they said...

Refused to refund my core charge because they said I didn't send it in the original box. After various emails back and forth (they wont' talk on the phone) They admitted that they did get my parts in a original AC Delco Box, but it wasn't the correct box, and still refuse to refund me. I sent the parts in the boxes that they came to me in. This is currently ongoing and I'm going to be contacting my credit card company because this seems incredibly fraudulent. My family and friends all used to order off of this website and unless this gets resolved none of us ever will again.