Received a reply from the Greek ombudsman for extra documents, like the e-mail and the e-receipt.
I also submitted an European small claims procedure to the court of Athens, thank you for the hint.
Contacted a lawyer for a case in Athens but I'm gonna wait a bit to see the result of these 2 actions first.
To reply to others, I spoke to a friend lawyer who said that in my country (also EU) this is a case that I can win, though nothing is guaranteed in courts.
Let me explain the reason why I do this, because some people think i shouldn't waste more money on this. I'm well off and I have money to spend. I absolutely hate how I was treated by them and cheated and their messages to me. To some emails they just don't reply. Also how they just postponed me some months because the device will be back.
I am willing and will spend a lot of money and energy to fight them. That is an illegal claim in the contract. Also, a tourist trip to Athens, in which I also pay them a "nice" visit doesn't sound too bad.
If somebody else has some other ideas on how to fight them, please share.
Yours, M (full of anger)