Hello there, @evansmuriu291. 

Let me share an update about the error message (Please enter a valid phone number including area code.) when a new user attempts to register to your account. 

We recently opened an investigation about this problem, and our product team is still looking for a fix for this unusual behavior. While they do, please get the user who is trying to accept the invite to go to accounts.intuit.com and create a new login. After that, send a new invite leaving the phone number field blank.

Also, I recommend contacting our Customer Support Team to add your account to the notification list. Meanwhile, if you want to cancel the account, ask one of our agents to check the charge and request a refund. 

Here's how to reach them: 

1. Go to Help at the top menu, then select Contact Us.
2. Enter the error message in the What can we help you with? field.
3. Click Let's talk.
4. In the Choose a way to connect with us page, select either Email us or Get a callback.

I've also included some articles in case you need some ideas about managing your account, transactions, and subscription: 

• QBO Self-help

• How to update your subscription and billing details

Thank you for your patience. Please know that I'm just a comment away if you need further assistance. Have a great day ahead.