AVG anti theft has locked my phone

I changed my sim. MyAndroid phone is now locked by AVG - I have used the technical support via email. I have received one email, then nothing. They don't reply to me. I have called and complained. They still will not do anything. 
Discraceful service!
I have logged in to try to get the unlock password, but it says I have no devices registered.
On the old site, my phone is registered, but it says I cannot access it. That I need to re register it and then upgrade to the new AVG.
How do I do that when my phone is locked?
I am reluctant to do factory reset as I have read another's attempt on here, which did not work. I don't want to bin the contents of my phone for nothing…
If AVG support will not / can not resolve this, my phone is rendered useless?
I would add that I have not registered a pin/unlock password, neither did I intentionally select Anti theft. 
There is no advice/warning with this facility to tip us off that a change of sim will lock the phone?
Do AVG compensate for the loss of this rather expensive device?
AVG have killed it
Can anyone help?

Hello Clayton,

I will certainly check this for you.

Your case is being handled by our mobile support team.

I have changed the case priority high, they will contact you as early as possible with a solution.

Your patience is much appreciated.