I've shared your account information with the team so that they can assist you further. Once the issue is resolved, you should be able to access your Contact Info page through your Settings and update your email address.
I am having a simular problem. When I try to enter my phone number to verify it says another account is already using my phone number. Can someone please contact me to help solve this problem?
Could you please specify the issue you are experiencing when trying to add your mobile number to your account? Let me know so that I can assist you further.