Clinic told me my PCP was 100% covered, receives bill one month later with no prior notice

For context, I scheduled a PCP appointment at a clinic I used to go to with the intention of also getting a psychiatrist referral due to my company changing insurance plans. When I checked in at the front desk, the receptionist confirmed my insurance and told me it would be 100% covered so there was no copay. I did not hear from the clinic until today – I received an automated text message saying I still have an outstanding balance that would be overdue in a few days.

Looking at the statement, my insurance only covered a third of the cost. I am extremely confused and stressed because I am stretched very thin this month for finances, and I was not expecting this notice. There was zero communication about any kind of bill since that visit – the automated text was the first indication that I owed anything at all, after being told I owe nothing.

I’m planning on calling the clinic on business hours but I have no idea what I can say or do. I am no longer on that insurance plan, and I don’t have it in writing that I was told I didn’t owe anything. Is there anything I can do to argue this, or am I just SOL for this?

TLDR my doctor told me my visit was covered and then slammed me with a bill 3 weeks later with no prior notice and I am sad