curl --request PATCH \
  --url https://us-merchant.sandbox.api-us.meridianapps.dev/v1/payment-links/{id} \
  --header 'Content-Type: application/json' \
  --header 'X-Meridian-Api-Key: <x-meridian-api-key>' \
  --header 'X-Meridian-Signature: <api-key>' \
  --header 'X-Meridian-Timestamp: <x-meridian-timestamp>' \
  --data '
{
  "reason": "Adjust collection amount",
  "creditAmount": "300.00"
}
'

import requests

url = "https://us-merchant.sandbox.api-us.meridianapps.dev/v1/payment-links/{id}"

payload = {
    "reason": "Adjust collection amount",
    "creditAmount": "300.00"
}
headers = {
    "X-Meridian-Api-Key": "<x-meridian-api-key>",
    "X-Meridian-Timestamp": "<x-meridian-timestamp>",
    "X-Meridian-Signature": "<api-key>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'PATCH',
  headers: {
    'X-Meridian-Api-Key': '<x-meridian-api-key>',
    'X-Meridian-Timestamp': '<x-meridian-timestamp>',
    'X-Meridian-Signature': '<api-key>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({reason: 'Adjust collection amount', creditAmount: '300.00'})
};

fetch('https://us-merchant.sandbox.api-us.meridianapps.dev/v1/payment-links/{id}', 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://us-merchant.sandbox.api-us.meridianapps.dev/v1/payment-links/{id}",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "PATCH",
  CURLOPT_POSTFIELDS => json_encode([
    'reason' => 'Adjust collection amount',
    'creditAmount' => '300.00'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "X-Meridian-Api-Key: <x-meridian-api-key>",
    "X-Meridian-Signature: <api-key>",
    "X-Meridian-Timestamp: <x-meridian-timestamp>"
  ],
]);

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

curl_close($curl);

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

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://us-merchant.sandbox.api-us.meridianapps.dev/v1/payment-links/{id}"

	payload := strings.NewReader("{\n  \"reason\": \"Adjust collection amount\",\n  \"creditAmount\": \"300.00\"\n}")

	req, _ := http.NewRequest("PATCH", url, payload)

	req.Header.Add("X-Meridian-Api-Key", "<x-meridian-api-key>")
	req.Header.Add("X-Meridian-Timestamp", "<x-meridian-timestamp>")
	req.Header.Add("X-Meridian-Signature", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.patch("https://us-merchant.sandbox.api-us.meridianapps.dev/v1/payment-links/{id}")
  .header("X-Meridian-Api-Key", "<x-meridian-api-key>")
  .header("X-Meridian-Timestamp", "<x-meridian-timestamp>")
  .header("X-Meridian-Signature", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"reason\": \"Adjust collection amount\",\n  \"creditAmount\": \"300.00\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://us-merchant.sandbox.api-us.meridianapps.dev/v1/payment-links/{id}")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Patch.new(url)
request["X-Meridian-Api-Key"] = '<x-meridian-api-key>'
request["X-Meridian-Timestamp"] = '<x-meridian-timestamp>'
request["X-Meridian-Signature"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"reason\": \"Adjust collection amount\",\n  \"creditAmount\": \"300.00\"\n}"

response = http.request(request)
puts response.read_body

{
  "paymentLink": {
    "id": "usmer-fh6vd59kdi6q4komfkygdhuf",
    "createdAt": "2026-07-02T20:32:35.000Z",
    "updatedAt": "2026-07-02T20:32:58.000Z",
    "linkToken": "e7a94c74-a72a-463e-a1f0-d882fdfad746",
    "userId": null,
    "status": "ACTIVE",
    "statusReason": null,
    "initialAccessBy": "2026-07-03T20:32:34.000Z",
    "merchantId": "usmer-rtn86be1xb9jzb5qwib6z0i9",
    "recurrenceType": "VARIABLE",
    "referenceId": "REF-VAR-1",
    "referenceLabel": "Variable Test",
    "description": null,
    "creditAmount": "300.00",
    "creditCurrency": "USD",
    "debitCurrency": "USD",
    "nextPaymentDate": null,
    "lastPaymentDate": null,
    "paymentAttempts": 0,
    "startDate": null,
    "endDate": null,
    "collectionCount": null,
    "customFields": {},
    "autopays": []
  }
}

{
  "validationErrors": [
    {
      "type": "InvalidFormat",
      "fieldRef": "<string>",
      "message": "<string>"
    }
  ],
  "message": "<string>",
  "errorCode": "<string>"
}

{
  "validationErrors": [
    {
      "type": "InvalidFormat",
      "fieldRef": "<string>",
      "message": "<string>"
    }
  ],
  "message": "<string>",
  "errorCode": "<string>"
}

{
  "validationErrors": [
    {
      "type": "InvalidFormat",
      "fieldRef": "<string>",
      "message": "<string>"
    }
  ],
  "message": "<string>",
  "errorCode": "<string>"
}