Reporting Services date parameter reverts to US format from AU by James Bashforth

I have come across a strange issue in SSRS that is integrated into SharePoint 2010. It occurs on reports with date parameters. When you select a date parameter you get the date picker and select your dates, all seems ok at this point and the date appears in AUS format as expected.. Once you then hit apply and run the report, the parameters switch to a US formatted date.

I have checked all the region settings of the servers and even built a vm and recreated the exact issue, I’m at a loss how to resolve this. The biggest problem now is when the user hits apply again I get an error as the date is no longer in the correct format