The tc.de website usually caters to Germans only so it is not really necessary to support more languages as they do only operate out of Germany.

For a french site you may visit http://www.thomascook.fr .

btw: Have you ever visted e.g. http://www.canalplus.fr/ and found a english translation??? Many french websites do not offer a language-choice as well...

Greetings - Dirk