Microsoft Hotmail Locked Out Due to Old Phone Verification Error

I cannot access my Hotmail account. I know the password and used to be able to log in without issue, but it now requires verification. Unfortunately, the verification message is being sent to my old phone number. I've tried to change the number before, but it requires an approval code. I need the permission code sent to my old phone number so I may update it. This needs to be handled right away—I've been battling for days with no one to talk to or assistance from customer service. Update my account's phone number or disable the verification. I can't access an account that I know the password for. This is ludicrous. Please do not make arbitrary requests for verification or comparable procedures; security is my top priority.