Hi, The Google help page here states "The questions we ask to verify your identity are intentionally difficult. If you’re unsure about an answer, provide your best guess. It also helps to submit your answers from a computer you've used in the past"
Based on what you have said this doesnt work, so you need a Plan B.
Unfortunatly Google are clear that they do not deal with ad hoc requests, and e-mailing them or calling them wont help. They beleive the password XXXXX form to be the only way in getting back into your account, and state each time you fill in the form it is treated independantly, so I can only suggest from a device you have already used previously (if you have used another mobile or computer) try and re-try completing the recovery form, providing as much info as possible each time.
They go on to state if you cant recover your account password XXXXX only other option is to setup a new account using a different username, sorry this wasnt the answer you wanted to here, but unlike Hotmail, Google do not have a option for human intervention.