Legal Question in Landlord & Tenant Law in Illinois

I can't tell what the problem is. But if they are violating the contract, that could be a default/breach and you'd have to see what the rights/responsibilities are on breach - notice and opportunity to cure??? Also depending on how much they've paid you so far, the right to evict may no longer be available and you could be looking at having to foreclose. Have an attorney review the contract with you.