Anti theft: can't use my phone!

Robbe, A known issue… Have a look @ this typical link (https://support.avg.com/answers?id=906b0000000LRS1AAO).
AVG Guru

The AVG anti-theft app locked my phone because I changed SIM. But I don't know my password and I don't know how to get it. I tried everything I could think of but I can't fix it, and I really need my phone to work.

I have tried logging in with the email adres which is referred to in the lock-screen, which is also my google-account, but that doesn't have any mobiles registered to it, according to the site.
I also tried my other email account, and tried to do 'forgot password', just in case I had registered it, but it doesn't get a mail to reset my password, so I don't think I used it to make an AVG account

I can't do anything with my phone, and I haven't found any help on the internet, since all the solutions have to do with the AVG account.
 

Yeah, I saw your reply on another post, and did it already, but I'm not receiving  a real answer, just an automaticly generated email telling me 'the request has been received'.

There is 'progress'. Now, when I want to login, I still can't. But when I use the 'forgot password' link, I do login, with my gmail. But there still isn't any option nor notion of my phone being registered to this account.

Robbe,
We see that our mobile support team has replied to your email query. Please check your inbox and spam box as well and reply to same email with your further query if you have any. Thank you.

Robbe,
We see that you have sent your request to our mobile support team and your case reference number is 03488063. Since it is an email only support, you will receive the email reply with a resolution after some time. Please be patient and wait for the email reply. Appreciate your understanding.