partsgeek.com Refused to Issue Refund in full Marlton new jersey

I placed a parts order for my car totaling $1151.10. I never received the parts so far. I started emailing partsgeek.com about the issue. They acknowledged receipt of the parts back at their warehouse. However, they have only refunded me $772.60 and they kept the rest stating that we charge restocking fees. They still owe me $378.50. This also included core charges for parts they never refunded back to me as of yet. They do not provide any manager you can talk to escalate the issue. A guy named LEE called me today disclosing himself as a call center manager and that he is "THE BIG BOSS" in the company. There is no one else above him. He also told me that I will not get anywhere trying to contact anyone else about the refund issue and then he hung up on me.