Hello,*I bought a cell phone from a seller, qualitycellz (with free returns). After re...

Hello,*I bought a cell phone from a seller, qualitycellz (with free returns). After receiving it, I realized that I really didn't care for it so I contacted the seller and asked if I returned it for this reason could I get a full refund. They agreed and I sent it back in mint condition (as I had just gotten it and was careful not to damage it). Yesterday, I finally received a refund from the seller, but it was HALF of what I purchased the phone for. I asked the seller why and they stated they would not issue a full refund because they received it "damaged". It certainly was NOT damaged when I shipped it. Looks like when I complained to them, they opened a case in the resolution center which IMMEDIATELY ruled in their favor. I tried everything I could on the website to try to appeal the case or literally anything to challenge this, but I couldn't find anything. Please help. I explicitly told them that I would only return the phone if I could be assured of a full and total refund.