PrestaShop 1.5 Expert Required

I need a Prestashop expert who can help me finish a modification to my ecommerce store. I have all the files which were working on version 1.4 but now need it implementing on v1.5.

Basically, the store sells items that are made to measure. The item has a base price but then a customer can put the width and drop of the item and the price updates automatically with ajax.

These details are then passed to the cart and also show on the invoice and order details.

Finally there is also the ability to press a button with 'free sample' which nulls the price and also has free shipping attached.

This project was started but I was let down by the developer so no need it finishing urgently. I would like you to prepare this on a test site first before implementing on the live store. I already have the calculator script with the figures I need.

Thanks