Mechanic did $2,800 in repairs without calling me first - am I obligated to pay?

I brought my car to a shop for an oil change and to diagnose a weird noise. Authorized a $120 diagnostic fee over the phone.

Shop called and said it's the wheel bearing, estimated $575 to fix. I said "let me think about it" and they said okay.

Two days later they call and say the car is ready. I show up and the bill is $2,847. They replaced the wheel bearing, rotors, brake pads, calipers, and did a full transmission flush. I NEVER authorized any of this.

Now they're holding my car hostage saying I can't get it back until I pay. They say I signed a work order that gives them authorization to "perform necessary repairs." I don't remember signing anything like that.

What are my options here? I'm in Illinois if that matters.

I went back and asked for the work order. They showed me a form I signed when I dropped the car off. It has a pre-printed clause that says "I authorize [Shop Name] to perform diagnostic services and necessary repairs to ensure vehicle safety."

That's it. No dollar amount, no specific repairs listed, nothing. Just that generic language.

They're saying that's my authorization. Is that actually valid?

Update: I sent them an email this morning laying out exactly what NinaL said. They called me an hour later, furious, saying I'm trying to "steal services" and that I signed authorization.

The manager said if I don't pay the full amount they'll put a mechanic's lien on my car. Can they actually do that?

Filed the AG complaint this morning. Reference number #IL-2025-XXXX.

Also called the local police non-emergency line. They said they can't get involved because it's a "civil matter" but they made a report for documentation.

Still don't have my car. This is insane.