Joomla Web Development

We have a range of web sites that require work from time to time to add functionality/ redesign parts of them. We would like someone to work on a part time, from time to time as required basis, who is: - Responsive (able to get things done on request within 24 hours) - Very experienced with Joomla (its component, modules and template modification) - Good PHP skills - Very good communication skills in English - Preferably based in Asia (i.e. timezone)