The user actually stopped responding to the ticket. I'm not sure if the user was able to get the charts working himself or not. Adding something like this is actually not supported however, since it requires some custom coding. As our support traffic has increased, we've been enforcing this more strictly.
Basically what you'll have to do is to set up filtering on one set of parameters. It'll apply the sorting on that one parameter and you'll have to add the other two filters into the query that is written. If you have any other questions I'll try to assist as much as I can.