Greetigns.
As Joomla! expert with nearly 10 years of experience I'm more than sure I'll finish this job as fast as possible with the best results.
I have mastered every aspect of Joomla! and I can fix probably every error and squash every annoying bug. Just check my feedback - most of it are Joomla-based tasks. I know I had few years break from Freelancer - as I have much more "external" contracts now.
I have great experience with Joomla! since version 1.x (and earlier - before Joomla! forked from "Mambo" CMS) - including probably everything from simple page setup, opgrades, to custom components, plugins, modules, templates, core files modifications (not recommended, but some clients demands) up to integration with other systems (frameworks, CMS, CRM, Cloud things [mycloud], etc).
Choose me and be sure everything will work just as it should - or even better.