Unauthorized "device payment eligibility check"

My wife is the primary account holder for our wireless devices, and the only listed account manager. Upon logging into our account this month, she saw a notice that a "recent device payment eligibility check" was performed on 7/10/2019 because of "a recent inquiry by you (or any account manager) about upgrading your device or adding a new line under a device payment agreement". We are the only two people on the account - I am not able to make such inquiries, and she did not make any inquiries for new lines or devices. We have the bill on autopay and do not log on for months at a time.

The notice was:

  • Posted to the Verizon wireless account dashboard/inbox, not email or physical mail
  • The account number was accurate
  • The name was incorrect (her maiden name was used, and her name has been legally changed for 6 years)

This appears to be an unauthorized credit check performed by Verizon. I would like to know how this was initiated and by whom, as my wife and I do not want any credit pulls against our accounts. The online chat feature is extremely unhelpful. The representative told us it is a soft check which occurs after surfing devices on the website which WE DID NOT DO, and to "rest assured there is nothing done with your account". 

I want to know what specific action(s) caused this letter to be sent and the credit check performed, and how we can prevent it from happening in the future.