curl --request POST \
  --url https://{workspace}.spreesuite.com/billspree/connections/update-connection \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "method": "Update",
  "action": "Update Subscription",
  "apiVersion": "v2",
  "connection": {
    "id": 1,
    "connectionNumber": "CONN-001",
    "tariffCode": "DemoPlan",
    "batchCode": null,
    "connRefNo": null,
    "description": null,
    "ts": 1,
    "connectionDate": "01012026",
    "paymentMethod": null,
    "connectionInputs": [
      {
        "name": "MeterNo",
        "value": "99999"
      }
    ],
    "meteredConnectionInputs": [],
    "address": {
      "city": "Karachi",
      "street": "Main Blvd",
      "countryId": null
    },
    "users": [],
    "meters": [],
    "accounts": [],
    "variants": []
  }
}
'

{
  "success": true,
  "statusCode": 200,
  "message": "Request Succeeded.",
  "error": null,
  "data": {}
}