i cant figure out the last little bit of this problem.

i cant seem to run the program. any help? 



private void button1_Click(object sender, EventArgs e)
        {
            double numOfItems = double.Parse(textBox1.Text);
            double numOfPounds = double.Parse(textBox1.Text);

            bool surchargeApplicable = true;

            string shippingMethod = "SSM";
            double surcharge;

            switch (shippingMethod)
            {
                case "SSM":
                    surcharge = 2.5;
                    break;
                case "ESM":
                    surcharge = 5;
                    break;
                case "SDM":
                    surcharge = 8;
                    break;
            }
            double finalAmount;
            double itemsAmount = 10;


            //Calculate Items amount
            finalAmount = itemsAmount;
            if (surchargeApplicable)
            {
                finalAmount = itemsAmount + surcharge;
            }
            finalAmount = finalAmount * numOfItems;

            //calculate Pounds amount
            double poundsAmount = 10;
            finalAmount = poundsAmount;
            if (surchargeApplicable)
            {
                finalAmount = poundsAmount + surcharge;
            }
            finalAmount = finalAmount * numOfPounds;

            label7.Text = finalAmount.ToString;

        }

        private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            string shippingMethod = comboBox2.Text;
        }

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Lyndsee Elizabeth