Hello Thierry-
I used Google Translate to read your question, so forgive me if I’ve misunderstood any part of it. Here’s the translation I used.
I managed to install your W3 Total Cache plugin, but when I activate it I can no longer view my website through a browser. I would love to buy the “Pro” version, but I would also like a technician to install it for me on my site and configure it correctly! My site is hosted on a dedicated server.
Can you give me a quote for a custom installation of your plugin please.
We do offer a plugin configuration service, which you can order directly from your WordPress Dashboard under the Performance > Support menu, or you can get in touch with the team using this form.
I’m sorry to hear about the issues with your website. Generally speaking, the most common cause of what you described is an issue with automatic minification. Usually disabling minify in your Performance > General Settings menu will restore the functionality of your site. If you can provide any details about what’s happening when you “can no longer view your website in your browser,” we might be able to help further.