reseting password on icloud.com says birth date is wrong but it isn't

I'm trying to help someone reset their icloud password that they've forgotten. We go to icloud,com and click the "forgot Apple ID or password" to get to the recovery page. Two options presented are send email link or ask security questions. They don't recognize the partially obscured email address and so we click the security question. The first question asks for the birthday but when we enter that it says it's wrong. Their phone will still log into icloud.com in Safari though (prompts for a touch id), if we do that and look in the account profile we can see the birthdate and it's correct and what we think it is. Their mac (and their phone) are the only two devices registered which is expected. Both devices are getting their icloud email. How do they change their password?