Creating a script to query a mailbox, copy its .csv attachment to a folder

Our site sells tyres, the daily stock-level from our supplier is sent via email as a CSV. I have created an import template (for the manual imports) in the All-in-One-Import WP plugin. This plugin has a scheduled auto-import function using a cron-job. I'd like to use this scheduled import, but the CSV needs to be modified before it is imported.

The CSV has approx 2700 rows. It arrives to an email inbox on same domain/server as the Wordpress-WooCommerce site.
It has columns for 'cost price' and 'sell price', (both are same value), the value in 'sell price' needs a fixed value added (not a percentage) - same value to all : +£1 fee and +£8 delivery - these are independent to WooCommerce fees and shipping.

I would like a price-quote for:
1. creating a script to query the mailbox on the server and copy its .csv attachment to a folder (on same CPanel hosting account as the receiving mailbox).
2. The email needs to be deleted after its attachment has been copied to the site-root/imports folder.
3. the filename of the csv must always be the same (the cron/import is set up to look for a file named 'tyres_data.csv' in the folder /imports.
4. The csv file should be deleted after successful import (or be overwritten by the subsequent csv files arriving each day).