possible gpl violation by webshop xt:commerce

Hi,

Just found the following issue:

The webshop xt:commerce, which is a fork of the GPLed oscommerce, doesn't 
provide it's latest version for download, but they still claim it's GPL.

Now, to get the source, you need to pay a "development- and support fee" of 98 
eur for twelve months.

So this seems to be a clear violation of the GPL. What's the next step? 
Writing a polite email to them probably. Can anyone help me writing it 
(preferrably in german), especially pointing to the correct parts of the gpl? 
(Contact me via jabber, see below)

-- 
Hanno Böck              Blog:   http://www.hboeck.de/
GPG: 3DBD3B20           Jabber: jabber@xxxxxxxxx

"Was berechtigt eigentlich jeden Computerbesitzer, ungefragt seine Meinung 
abzusondern?"
Jean-Remy von Matt

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