- he isn't getting his own account, but gets logged in as my super administrator account. This isn't supposed to happen ofcourse and is absolutly unsafe (let's make it easy to hack the website).

If he logged into the site through normal means then clicked the FBC button he just synchronized the two accounts. This is normal behavior. You can't simply login with FBC and instantly have SA access.

- he couldn't log out using the logout button. He had to go to the logIN button to logOUT

As with the Sign In button after login with FBC there will be a Sign Out button. Clicking this will logout. Normal logout through CB or Joomla will not work as they must be logged out through the API. The normal logout button is removed when logged in via FBC.

Could it be that when i tested the plugin using the clients facebook inlog-codes, the plugin somehow linked these codes to my super administrator account (i was logged in on the backend)???

Yes, if you were logged into Joomla already on frontend this is exactly what it'll do.

If this is the case, how do i disable this link??? By deleting my super admin account?

Simply edit the user from backend and empty the "Facebook ID" field.

And the log out button surely only links to the cb login-module....so hitting logout doesn't have any effect on the facebook login??

You need to use the logout button added by the plugin to the login module.

Do you get your own account when you login or do you aswell get the mkbdigitaal account?

You get your own account, but you can also link your FBC account to an existing login.

Mangiok wrote: I have a log out problem as well.

I can see and click on logout and when I do, this is what I get
Session expired or cookies are not enabled in your browser. Please press "reload page" in your browser, and enable cookies in your browser. Please refresh/reload page before filling-in.

Please ensure you're using CB 1.4, if so please navigate to CB Configuration and on the Integration tab set Enable anti-spoofing sessions checks to No. Once done please test and confirm if issue still present.