Energy company switching unannounced

I recently received a notice from Discount Power that I was overdue on my electricity bill and they are threatening to shut off my power in a few days.

I have never used Discount Power and am currently in the middle of a 3 year contract with Energy Texas with no missed payments.

I never received notice from ERCOT that my energy providers were switching and I am missing information such as an ESI ID so I cannot make a Discount Power account to investigate further.

I’m planning on contacting both companies in the morning but was curious if anyone has had similar issues and how they resolved them.