AVG installed itself

AVG installed without my permission, and now I can't uninstall it. I have tried using the different tools provided by your website, but it is simply not uninstalling. I used the uninstalling tools, it confirms that it has uninstalled, then when I restart the computer it's still there!
I can't even terminate the task on task manager. 
I started another thread with the same problem. Your answer has been "we'll email you". and in the email all I'm getting is the link to the tool that I HAVE ALREADY USED. You are not offering me a solution, you are just redirecting me to the same tool that I have used previously but HAS NOT RESOLVED the problem.
I repeat: AVG installed itself without my permission, and now I can't get rid of it. It is simply NOT ACCEPTABLE
I need a solution that will work, not the link to avg clear because it does not work in my PC.
I also need to know how and why it installed into my PC without my permission, so I can stop it from installing itself again.

Hello Marga,

We're sorry for the inconvenience caused.
To fix this issue, we request you to get connected with our additional support.
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