I'm not sure what to do – but here's the story. Last summer - in July - I bought a used Mac Pro 12 core. The Apple Hardware Test displayed an error code, so I sent back the back. The seller changed some parts and I received the Mac again … with the error code. Or another error code, I don't remember. I sent it back again, it came with back a second time with the error code. The Mac behaves very weirdly, and I'm not sure if it has something to do with that. Apparently, the error code is just a graphic card thing - something users on here told me as well. The Mac is covered by the seller's warranty, so I shouldn't have spent any money on it. The seller is in a different country (in Europe) than me, so when I sent it back, I payed the postage. He said he would give it back to me later. That's almost a year ago. He did send me a part of the money, but he split everything between him and me, so basically, 50% are missing. I also bought new RAM because he asked me to do so, I only bought 2 or 4 GB I think, just to test it. Well, I'm unsure what to do? This seller seems to be in a big chaos. And the warranty ends in July. I wrote him again - he didn't understand what I was talking about. After I explained, he didn't respond anymore. Should I just go to court with him? He also removed warranty on all of his products after what happened with me, I guess it cost them a lot of money - but it isn't my fault either if they sell Macs that behave weirdly and have error codes. I had plenty of different error codes with different RAM, different logic board and different graphic cards. I've been using the Mac now and it works, but, as I explained in other threads, there's always these small weird things… What would you do in such a case? If this happened to you?