STEP 1: Open attachment. Form will look like this.
This is a switch request and at the bottom they will let you know what cars will need rejected. If the form does not state the reject reason, follow-up with them to confirm the reason. A detailed reject form should be sent with their switch request that explains what is needed. Form shown below.
They are known to send in multiple forms. Sometimes a BOL will have a car that isn't billed. More than likely that is a reject car. Just explain that the car in question was not billed, and you did not receive a reject notice.
Here is a BOL they sent in on the rest of the cars. BNSF 498090 was not billed.
Essentially, all forms should be attached to one email but if they aren't just ask if the cars in question need to be rejected and the reason for the reject.