MOBILE AVAST

I wanted to change sim cards and as soon as I changed it the siren went on once I tried to install. I dont have the pin avast sends because it goes to the second line that I registered which didnt receive any pin. I went on my account online and can see all activity but once I try to send an sms to unlock and stop the siren it says it cant find the phone and error message. How can I stop the siren and unlock ??

http://www.avast.com/faq.php?article=AVKB135