A page ( https://github.com/pricing , I am a verified teacher, what happens if I already subscribed to co-pilot ) clearly tells me to contact support. I've decided it's simply impossible to contact anyone at github, every attempt just leads to an automated reply and my post being closed. I'm not sure there is anyone there. I tried posting ont he help forum, where I (of course) never got a reply.
This has made me make sure nothing I care about is only on github -- as I don't expect to any recieve any help if I have any other problems in future. I should of course be careful anyway, but when you hit these problems you realise quite how hard it is to contact any modern large company.