validation?

Last Wednesday Oct 16, 2019, I helped Mimi, my friend to create a new Fizz account with her email address (yahoo.com) and ordered a sim card, which is sent to her home by mail. She signed up for the special of $20 plus voicemail of around $1. I have paid for the simcard already with my credit card. The next day when I logged onto her account to check but couldn’t. An error message is that the password became invalid because an email of validation was sent to her by Fizz but she did not reply within 24 hrs. Obviously she didn’t, because she couldn’t access to the internet with no phone service.
This afternoon, she came to my office to log on to her Yahoo email, in order to see if she could open the email Fizz had sent her last week, hopefully she could log onto her Fizz account by changing her password. However, when she logged onto her email address, Yahoo asked for her to her cellphone number in order to text her a validation code to sign in.
Now, this is where she is stuck. She no longer has a phone plan therefore her phone cannot receive any validation code from Yahoo. Therefore, she cannot even check the email Fizz sent her last week. She cannot sign in the Fizz account created with her email address either, because the password is no longer valid.
Now, what should she do to activate the account created last Thursday?