Don't have access to the secondary email address so can't recover the account that way. Have also tried to use the questionnaire at https://account.live.com/acsr without success, it just comes back straight away with an email saying not enough information was provided.

I have provided it with 3 recent email addresses and 4 recent email subjects which seems like it should be enough, yet it doesn't work.

What can I do to regain access to my account as it contains important emails that I must recover?