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We are a direct mailer company that mails discount booklets monthly in pre-established mailing routes which we call zones. Clients pay us to include their advertisements in our mailer in their preferred zones. What we are attempting to accomplish is to design a service enrollment and payment portal that calculates the selected "Zone" cost, multiplies the cost times the number of months selected, and presents a subtotal in the "subtotal" field. Then we need to be able to calculate a discount based upon a text entry entered into the "Promo" field. There will be three promo codes, one each, for 5%, 10%, and 15% discounts. The discounted rate should then be displayed in the total cost field. Once the calculations are complete the total cost must be passed to our paypal account and generate an invoice for a recurring payment corresponding to the number of months selected. For example, if a client opts to mail three zones at $800/month for October, November, and December 2016 the total of $2400 dollars should pass to paypal as a three time recurring payment to be drafted on the 15th of the month prior to the mailing. If a new client enrolls after the 15th day of the month for the upcoming month they should be billed immediately for the first month and recurring for the remaining months. For example if the client enrolls on the 20th of September for the October, November, and December 2016 mailings they should be immediately billed for the October mailing and be left with two recurring payments to be paid on the 15th of October for the November mailing, and the 15th of November for the December mailing. If this cannot be accomplished using PayPal we are open to suggestions.