Why solve matters with lawyers if you don't need to? If there's a failure of understanding, possibly due to language issues as the previous commenter suggested, then trying to establish a dialogue and trying to explain the matter to them would be a far easier (and cheaper!) option for everyone, regardless of locality.
It doesn't help that the GPL is not an easy document to read by the way :-/
It doesn't help that the GPL is not an easy document to read by the way :-/