PHP - Good with Databases for ongoing project

General information for the website: We are a leading comparison website for the property industry
Database management system (DBMS): MySQL
Description of requirements/features: We use PHP, MySQL, JQuery, JS, HTML, CSS

We are looking for a company/someone who can maintain and update the backend (only) of our existing Db.

We already have plans to begin the next phase of work. We will start by asking you to fix some issues which are either annoying or broken before moving onto any of the major changes. This will allow you to understand the code as it's a complicated web application.

Depending on the size of task, some work will be pph and some on fixed price.

You MUST be English speaking.
Extra notes: Remember when you provide me with your prices per hour, that you are in a global market place. The UK currency is very strong and buys a lot hours globally - so ROI globally is a main factor.

Now for unusual honesty...

We have worked with many developers over the years. Some have left because they couldn't handle the pressure and others naturally just move-on due to other commitments.

2 things are important to us as a company, and we will not comprise on:
Quality - you must be able to follow designs accurately and have some degree of aesthetics.
Delivery - we have a good idea how long things take, and when you estimate your own time, you MUST deliver to that date. Fully tested, and working; not then spend 2 more days fixing your own problems and expecting us to pay you for it. Neither, do we expect estimates to be so excessively long to guarantee you hitting delivery dates - which is common IMHO.

NDA's will be signed.
All work taken through PPH