Can I just be on straight Medicaid? [Illinois]

My PCP and Urologist accept different forms of Medicaid. I called my PCP, they said call Medicaid & see if you can opt out of having to choose a specific plan.

I called Medicaid, and they said no, you don't have that option. Call your PCP and persuade them to enroll you in Meridian. Wtf??

My only option is Aetna, which they both seem to accept, but the reviews are really bad here. I mean, I am trying to prepare for a surgery this year. What should I do?