I think the eye center tried to scam us in order to make more money for their services. What can I do?

Duplicate post.... see https://www.agingcare.com/questions/WHy-did-the-Kleiman-Evangelista-Eye-Center-in-Arlington-Texas-charge-my-mother-3000-for-doing-her-ca-430409.htm

Have you called the billing office to ask them why they are sending your mother a bill for the surgery if they have also billed Medicare?

Usually, when you are in a surgical/hospital situation, you sign a statement that you will be responsible for charges not paid for by insurance. If Medicare hasn't paid the bill yet, they are going to continue too bill your mom until Medicare pays.

Did your mom get preauthorization for the surgery?

Have a conversation with the billing office tomorrow.

Bear in mind that Medicare does not cover all services, only about 80%. It's not a scam unless you can prove the services were unnecessary or not signed for.