"operation": "createSubscription", "account_no": null, "service_id": "SV12345", "start_date": "2025-13-01" // invalid month
"account_no": "1002345", "start_date": "2025-02-28" orcommn-12004
"account_no": "", "start_date": "2025-02-30" "start_date": "2025-02-28" "account_no": ""