Psn account banned because of hackers

I have a psn account which is used by my autistic son because he has diminished responsibility and has no bank account. While he was in a community chat he left his PlayStation briefly to look at his tablet and while he was doing this a link popped up in his community chat saying click here for free coins and it looked like he had sent it himself. My son panicked and came running to tell me. I told him to quickly message the community and tell them not to use it as he didn't put it up and we thought the account must have been hacked. He did this and a few seconds later the same link appeared on screen. I was standing with my son when this happened and was horrified to see something appear on screen as though he had typed it when I knew he hadnt. So I told him to sign out and I went to my home pc, logged into pen and changed the password on the account. Next thing I know my account has been permanently banned. The reason being I apparently tried to defraud users by sending a scan link on the network. There was no contact from Sony to warn me that this had happened until after the event despite having a pen account for years and spending several thousand pounds over this time and also having no suspicious transactions EVER. I have contacted Sony and am still waiting for the matter to be dealt with. I am disgusted by this treatment as they decided very quickly that I did this, they should be able to overturn this decision just as quickly. Now they say they have to investigate further. Why did they not do that in the first place? I am sickened and angered by Sony's blame first and don't even bother asking questions later policy as the email I eventually received gave me no way to protest. All it said was your account has been permanently banned for reasons of trying to defraud community members and this decision will not be overturned. I still don't understand how someone can post on psn and make it look like you did it yourself. I will update this post if and when I hear from sony.