Your content is copyrighted and you are within your rights to demand they take it down.
You are offering use of your source code, which is your copyrighted work, under the terms of the GNU LGPL. Your product descriptions, screenshots etc. are not covered by this license. The license states
(1) we copyright the library, and (2) we offer you this license, which gives you legal permission to copy, distribute and/or modify the library.
So they have copied your work under this license, but the terms of the license state that the license must be included without modification. From your description of the site it appears that this is not the case, therefore they have violated the license and thus have no right to distribute your copyrighted work. They also have no license to copy your product descriptions, documentation and screenshots, although it may be argued that changelogs form part of the source code.