// Create a checkout preference
        private Preference CreatePreference(Int16 amount, string email)
        {
            // Set Checkout Helper
            CheckoutHelper ch = new CheckoutHelper();

            // Create token
            Token token = ch.CreateAccessToken(Properties.Settings.Default.ClientId, Properties.Settings.Default.ClientSecret);
            ch.AccessToken = token.AccessToken;

            // Set item
            Item item = new Item();
            item.CurrencyId = Properties.Settings.Default.CurrencyId;
            item.Description = Properties.Settings.Default.Description;
            item.Id = Properties.Settings.Default.ItemId;
            item.PictureUrl = Properties.Settings.Default.ImageUrl;
            item.Quantity = 1;
            item.Title = Properties.Settings.Default.Title;
            item.UnitPrice = amount;

            // Set preference
            Preference preference = new Preference();
            preference.BackUrls = new ResponseUrls();
            preference.BackUrls.Failure = Properties.Settings.Default.FailureUrl;
            preference.BackUrls.Pending = Properties.Settings.Default.PendingUrl;
            preference.BackUrls.Success = Properties.Settings.Default.SuccessUrl;
            preference.ExternalReference = "my id";  // your id for this transaction
            preference.Items = new ItemList();
            preference.Items.Add(item);
            preference.Payer = new UserEx();
            preference.Payer.Email = email;
            preference.CustomPaymentChoices = new PaymentChoices();
            preference.CustomPaymentChoices.ExcludedTypes = new IdList();  // remove ticket and bank transfer options
            preference.CustomPaymentChoices.ExcludedTypes.Add("ticket");
            preference.CustomPaymentChoices.ExcludedTypes.Add("bank_transfer");

            // Create preference
            preference = ch.CreatePreference(preference);

            return preference;
        }
    // Create a checkout preference
    private Preference CreatePreference(Int16 amount, string email)
    {
        // Set Checkout Helper
        CheckoutHelper ch = new CheckoutHelper();

        // Create token
        Token token = AuthHelper.CreateAccessToken(ConfigurationManager.AppSettings["ClientId"], ConfigurationManager.AppSettings["ClientSecret"]);
        ch.AccessToken = token.AccessToken;

        // Set item
        Item item = new Item();
        item.CurrencyId = ConfigurationManager.AppSettings["CurrencyId"];
        item.Description = ConfigurationManager.AppSettings["Description"];
        item.Id = ConfigurationManager.AppSettings["ItemId"];
        item.PictureUrl = ConfigurationManager.AppSettings["ImageUrl"];
        item.Quantity = 1;
        item.Title = ConfigurationManager.AppSettings["Title"];
        item.UnitPrice = amount;

        // Set preference
        Preference preference = new Preference();
        preference.BackUrls = new ResponseUrls();
        preference.BackUrls.Failure = ConfigurationManager.AppSettings["FailureUrl"];
        preference.BackUrls.Pending = ConfigurationManager.AppSettings["PendingUrl"];
        preference.BackUrls.Success = ConfigurationManager.AppSettings["SuccessUrl"];
        preference.ExternalReference = "my id";  // your id for this transaction
        preference.Items = new ItemList();
        preference.Items.Add(item);
        preference.Payer = new UserEx();
        preference.Payer.Email = email;

        // Create preference
        preference = ch.CreatePreference(preference);

        return preference;
    }