curl --request POST \
  --url https://coreapi.io/api/payment-plans/{id}/extend \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "installments": [
    {
      "dueAt": "2026-08-05",
      "amount": 595
    }
  ]
}
'

import requests

url = "https://coreapi.io/api/payment-plans/{id}/extend"

payload = { "installments": [
        {
            "dueAt": "2026-08-05",
            "amount": 595
        }
    ] }
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({installments: [{dueAt: '2026-08-05', amount: 595}]})
};

fetch('https://coreapi.io/api/payment-plans/{id}/extend', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://coreapi.io/api/payment-plans/{id}/extend",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'installments' => [
        [
                'dueAt' => '2026-08-05',
                'amount' => 595
        ]
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

{
  "id": "10000000-0000-0000-00e0-000000000001",
  "invoiceId": "10000000-0000-0000-0003-000000000001",
  "status": "active",
  "totalAmount": 1190,
  "currencyCode": "EUR",
  "paymentMethodId": "10000000-0000-0000-004f-000000000001",
  "createdAt": "2026-07-05T16:20:00+00:00",
  "completedAt": null,
  "brokenAt": null,
  "canceledAt": null,
  "brokenReason": null,
  "installments": [
    {
      "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "position": 1,
      "dueAt": "2026-08-05",
      "amount": 595,
      "status": "open",
      "paidAt": null
    }
  ]
}

{
  "status": 422,
  "type": "PAYMENT_PLAN__SUM_MISMATCH",
  "title": "An error occurred",
  "detail": "The installments must sum to the open amount of the invoice."
}

{
  "status": 422,
  "type": "PAYMENT_PLAN__SUM_MISMATCH",
  "title": "An error occurred",
  "detail": "The installments must sum to the open amount of the invoice."
}

{
  "status": 422,
  "type": "PAYMENT_PLAN__SUM_MISMATCH",
  "title": "An error occurred",
  "detail": "The installments must sum to the open amount of the invoice."
}

{
  "status": 422,
  "type": "https://tools.ietf.org/html/rfc2616#section-10",
  "title": "Validation Failed",
  "violations": [
    {
      "propertyPath": "installments[0].amount",
      "message": "This value should be positive.",
      "code": "<string>"
    }
  ]
}