Diving into this, I'm just trying basic calls and going through the response.
Is it not possible to search for customers based on name such as you can by email (see screenshot below)?
where={"lastName.value":{"$contains":"smith"}}
Response text: {"errorCode":10410,"description":"Resource customers version v3 does not have a definition for field lastName.value","uri":"https://docs.worldsecuresystems.com/developers/","extraInfo":null}
Where is the list of fields you CAN search by if you can't search all fields?