WP Contact form 7 issues calculating diff amounts for different customers

Hello I have set up a form to send quotes to customers automatically. It works most of the time but for some customers will give the wrong amount by much less than it should be. I would also like the email that is sent to the customer to be in a better format more professional looking. The form also gives a discounted price for the customer if they reply within 60 minutes I would like to automate this so they can click a button from the email to take them to a page on my website to confirm the booking and be sent to my paypal site to make payment for the amount they have got whether it be the discounted amount or the full amount depending if they responded within the 60 mins. When they confirm the booking and pay I would like my site to send a email to my email giving details of the job and invoice to the customer. Site is wordpress