Comcast Landline breached

My bank notified me that there was a breach that was executed by using my Comcast landline to complete the secondary authentication.

The bad actor was able to direct my bank's system to send the verification code as a phone call. The phone never rang at my home. 

With this, they were able to access my account - but the Bank's fraud department identified the unusual activity, locked the account down, and notified us.

I called Comcast support and was transferred six times. No one wanted to hear that they were breached.

Each representative passed me on to the next department to address the issue.

They all gave the same response, "Our system is secure and shows no record of a breach". 

I ask rhetorically - isn't that a sign of a successful breach, not leaving a trail?

I wish I could contact Noopur [Edited: "Personal Information"] directly - I could share the voice of the customer about how poorly the security support team represents the company.