After about 4 years of happily (VERY HAPPILY) using ubuntu I am facing a wall.

My company has changed the network configuratin, now we use a proxy with user name and password authentication. I get a "blabla@blabla.com" username for that proxy.

Firefox configuration was easy and works ok.
Configuring system proxy is a nightmare because of the "@" in the user name. I have try to escape it several ways and in several files but still no success. Now, I can navigate the internet, but I cannot do apt-get install, update, etc ...

Please, help!