They appear to have realised that the Kraken migration hasn't been plain sailing ...
"Oops, something isn’t right. Have we told you ‘We’re making some changes’ in a letter or email? Please call 03330 069 950 if you can't get into MyAccount."
phoned them and they sent me link to set a new password, that failed, they sent another link, that also failed, so now apparently I need to wait until the morning.
Their parting words were "it's not a problem", my parting words were "it is a problem" ...