It would make more sense to first back up all your stuff switch all accounts to the new email address, set up email forwarding for a month, and then issue the c

It would make more sense to first back up all your stuff switch all accounts to the new email address, set up email forwarding for a month, and then issue the chargeback. From what you are saying this is actually an easier process and unlike your suggestion will surely succeed 100% of the time. Then you aren't anyone's hostage.