Since its illegal for Microsoft to hold your CVV number surely the obvious thing to do would be to simply ask for that before allowing you to change any of your address/password details. Call centre staff can't have that info as quite simply Microsoft are obliged not to hold it so no number of calls would result in the "hackers" having access to your account.
The call centre staff shouldn't have access to your password either, if you forget it they should simply email a new one (auto-generated, again they have no access) to your already registered email address (which with the above can't be changed).
Register
CVV
Since its illegal for Microsoft to hold your CVV number surely the obvious thing to do would be to simply ask for that before allowing you to change any of your address/password details. Call centre staff can't have that info as quite simply Microsoft are obliged not to hold it so no number of calls would result in the "hackers" having access to your account.
The call centre staff shouldn't have access to your password either, if you forget it they should simply email a new one (auto-generated, again they have no access) to your already registered email address (which with the above can't be changed).
Problem solved.