Family Link Stop Supervision option is not available

My son is 15 and I would like to stop his phone being controlled by Family Link.

The published solution for this is to access his account settings in Family Link on my phone, select Account Info, select Stop Supervision.

But that option does not exist for me.

I have checked his DOB, I have checked I am logged in using the correct account, I have checked that 13 is the permitted age in my country. I have stopped and started both phones. I have re-installed the app on both phones. No matter what I do, the “Stop Supervision” option is not available.

I can’t recall if I set it up after he was 13 or not not. Either way, he never got an email asking him did he want to stop supervision.

This is driving me nuts!