WordPress Abandoned project takeover

Abandoned WordPress Project — Car Rental System Rebuild

Industry: Car rental (Spanish market)

PHP 8.x WordPress MySQL JavaScript

The situation

A car rental company operating in Spain relied on a custom WordPress plugin for fleet management. It was a classic case of an abandoned project — the original developer stopped maintaining the plugin and went silent. The client was left with a working but increasingly problematic tool that no one could fix or extend. They needed a WordPress developer who could step into the existing codebase and take over.

The problem

The plugin had tens of thousands of lines of code with zero documentation. Before I could change anything, I had to go through the entire codebase and understand how everything fit together. On top of that, there were specific bugs — the system miscalculated rental prices, and the availability logic didn't properly account for vehicle preparation time between rentals. In practice, customers could book a car that wasn't physically ready yet.

What I did

I started with a complete code review. Only then did I move on to actual changes. The biggest change was a brand new rental agreement system. Previously, staff had to manually gather data from several different places in the system to put together a single contract. I built a module that automatically pulls all the necessary information — customer data, reservation details, rental conditions, pricing — and generates a ready-to-sign agreement. The customer signs it on the spot, on a tablet. The contract is automatically saved and emailed to both the customer and the rental company owner.

  • Fixed the pricing mechanism that was generating incorrect amounts
  • Corrected the availability logic — the system now properly blocks vehicles during cleaning and preparation
  • Created a role-based access control system — not every employee needs to see everything
  • Added a reservation overview that didn't exist before
  • Built a one-click export module for completed rentals for the accountant — replacing hours of manual data gathering
  • Redesigned the entire interface with a mobile-first approach, since staff primarily use the system on phones and tablets

Result

A system that previously required constant manual oversight now runs largely on its own. The time needed to process a single rental dropped significantly. The accountant generates reports with one click instead of spending hours compiling data manually. The client still works with me — we're currently integrating GPS devices installed in vehicles.

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