我在JS中有以下代码：

// Function to feed the API
function FeedAPI() {
    // Define the API endpoint URL
    var apiUrl = "https://ifthenpay.com/api/gateway/paybylink/XXX-XXXX";

    // Define the JSON API body
    var apiData = {
        "id": "1234",
        "amount": ValueSelected(),
        "description": $('#name').val(),
        "lang": "en",
        "expiredate": "",
        "accounts": "",
        "selected_method": PaymentSelected()
    };
    console.log("API data: ", apiData);
    
    // Use jQuery's $.ajax() function to make the request
    $.ajax({
        type: "POST",
        url: apiUrl,
        data: JSON.stringify(apiData),
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function(response) {
            console.log("API response: ", response);
        },
        error: function(xhr, status, error) {
            console.error("Error: ", error);
        }
    });
}

但得到这个错误：Access to XMLHttpRequest at 'https://ifthenpay.com/api/gateway/paybylink/XXX-XXXX' from origin 'https://example.com' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: The 'Access-Control-Allow-Origin' header contains multiple values '*, *', but only one is allowed.
我正在Windows上使用Plesk，并且已经尝试将web.config文件设置为以下内容：

<httpProtocol>
  <customHeaders>
    <add name="Access-Control-Allow-Origin" value="*" />
    <add name="Access-Control-Allow-Headers" value="Content-Type" />
    <add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS" />
    <add name="Access-Control-Allow-Credentials" value="true" />
  </customHeaders>  
</httpProtocol>

在这一点上，我尝试了一切...有人能帮忙吗？