Acumatica How To Update Default Customer Payment Method with API?

I can't find the good method de update Default Customer Payment Method with API :

The PUT is : https://localhost/XXXXXXX/entity/Default/20.200.001/Customer/?$expand=PaymentInstructionsThe body sent :

    {"id": "d9f39ef9-fc6b-ee11-a81d-6045bd6d244f","PmtMethod": {"value": "VCFON"    },"PaymentInstructions": [        {"id": "90871690-87eb-ee11-a822-6045bd6d244f"        }    ]        }

The first Id is the CustomerId. The second Id is the specific customer payment method I need to put as default customer payment method.I have a 200 OK but without any modification.