I purchased the item--3rd Generation MK802 II Android 4.0 Mini PC Google TV Box Internet Wifi Player,Item Id: 140840190119 from hopezone001, about one week after I got the item, I found that every time when I installing the Apps it says No SD card, I contacted with the seller, they let me change another SD card, then I purchased another SD card, it still same as it was; I e-mailed the seller, they said it has software problem, they sent me the website link and encouraged me to download from website and upgrade the software, I told them I'm not a computer guy i am just a ordinary user, I could not do that. but they keep telling me to do the upgrade according to their directions, I tried but it getting wrose, it even cann't turn on the WiFi after upgraded the software. seller asked me to send it back for exchange, but the postage cost even more than I buy a new unit and the seller is not willing to cover it, but I think this postage cost due to the seller sent me the defective item with software problem, so the seller should cover it, now we are in dispute, and they didn;t even answer my e-mail, what shoul I do now?