I have use this code for send value and hit api. But I have face a problem multiple value not send.

function CancelSubscription() {
    var UserID = "@UserId"; // without send this It's working, but i have send this it's not working
    var SubscriptionID = "@SubscriptionID";
    var data = new FormData();
    data.SubscriptionId = SubscriptionID;
    data.UserID = UserID;
    var apiurl = "https://localhost:44356/api/Subscription/UpdateCardDetail";
    $.ajax({
        type: "POST",
        url: apiurl,
        data: JSON.stringify(data),
        datatype: "json",
        contentType: 'application/json; charset=UTF-8',
        success: function (response) {
            if (response.isSuccess == true) {
            }
        },
    });
}