Plugin for Prestashop

I am looking to develop a plugin for my PrestaShop website. For every order placed, points will be awarded to customers. For instance, for every euro spent, the customer will earn one point in their reward pot. Once a customer accumulates 200 points, they will be entitled to a 10% discount, which they can use immediately or within a maximum of 3 months. I would appreciate it if you could provide me with a proposal for the development of this plugin. I would like a fixed price for the deliverable. No additional fees unless I request something to be added.