Got A Bill For A "medical Evaulation" That Was Supposed To Be Free

I started a process with a clinic to see if I'm eligible for a medical procedure. The process included filling an intake form and having a 10 minute zoom call with a nurse to see if I'm eligible. At the end, even though I was eliglble, I opted to not work with the clinic.

Today, ~3 months later, I get a $530 bill for a "diagnostic evaluation" from the clinic for that 10 minute zoom call.

I was never told that the evalutation cost any money nor there is any indication about it in their website. It's common practice for these kind of clinics to provide a free, no strings attached consultation so I find it very odd - I'm suspecting that they may have slipped it somewhere in the intake docs I had signed, but they were e-signed and I didn't get a copy so I cannot say for sure

I'm going to give them a call next week to understand what's going on and hopefully have them rescind the bill, but this reeks of malice and my gut feeling tells me they'd say something along the lines of

"the evaluation fee is typically waived if you use our services, but since you didn't...."

So assuming they won't budge:

1. Should I say anything else or just ask for the legal documents I allegedly have signed agreeing to that?
2. If there isn't any legal document, can I just inform that that I'm not willing to pay and move on with my life?
3. If I did in fact inattentively signed a doc as part of my intake forms, can I do something about it?

Thank you