You will need to setup the new sim card before you can disable everything.
As long as avast does not recognize the new sim card as "legitimate", it will keep running and sending messages.
If it didn't do this, each thief could easily disable it and that is not wanted ofcourse.
Follow the second link, after that make the changes to the settings as you want to have them.
Deleting the phone from your account only prevents you from sending commands to it from your account,
it doesn't stop avast from working.
I wasn't even aware that Avast send text messages from the phone
It is mentioned on the website, here on this webboard and in the manual. Sorry to hear you had to learn it the hard way. I know many (most?) people don't read manuals, but they often have things in it that are really useful to know.
About your ticket, have patience.
The ticket system is cluttered at the moment and avast is really working hard to solve things.
Don't create a new ticket or change the current one.
If you do, you will be put back at the bottom of the stack and you will have to wait longer.
Only thing I (and most others here) can do is giving you information.
Just like you, I am only a avast user.
