Unfortunately there is not much you can do. If the state has not sent you a letter, explaining the issue and you are unable to speak with someone, you need to have more information to understand why they are taking so long to process your return.
Here is Illinois Department of Revenue contact information
Telephone Assistance
To receive assistance by phone, please call 800 732-8866 or 217 782-3336. Representatives are available Monday through Friday, 8 am - 5 pm. Our TDD (telecommunication device for the deaf) number is 800 544-5304.
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