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Why the bitcoins was not returned to me
The reason is simple - they did not return bitcoins because they may not.
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Eeee, as I said. It is hard to write such text in foreign language ;-)
I misunderstood english or you misunderstood my text.
It is not needed to return bitcoins because the convention does not force it. The convention is to pay dollars whenever possible. And when in doubt, always pay dollars.