Turns out I have a debit card on file rather than a credit card. I have many debit cards but no credit card. Definitely not prepared to do a facial scan so no chat for me for a while!
So I can’t access my chats because of the UK’s Online Safety Act. The OSA isn’t Substack’s fault but I thought that as they have my credit card then everything would be OK. The next step invites me to verify my ID with facial scans with a company I’ve never heard of. Not sure this is quite what I expected!