I need a PHP coder to modify our existing booking system to suit ad-hoc orders

I need a PHP coder to develop a new feature on our website. This person must be OK with working on a site that has been coded by others.

Our existing customer 'log in' booking journeys and back-end admin system needs to be modified so we can take orders from 'ad-hoc' customers without having to log in.

The site is written in core PHP (version 5.6.40) and there's no framework used so the existing code will firstly need to be reviewed to understand how it flows.

This feature needs to be added to our site before I sell it so I am looking for a cost effective solution.

I have written up development notes for the work that is required but before these are submitted, we must have a Skype call and screen-share so I can show you how the new feature will work and what needs to be done to our existing booking journeys and admin functionality.

Brgds - Martin