Greetings!

I would always recommend phone support over the email support whenever possible. This way, you can get a live person (or their manager) to deal with.

If you do decide to do this, a recommendation I would give would be to have a list of the steps you did to try to correct the situation (i.e., hard reset, reloading firmware, etc.). This way, you can short circuit any scripts that they may have. Make sure you get the rep's name and ask to speak with a supervisor if things are not going well.

Note: I am not affiliated with DNNA or Rio (other than as a beta tester), so I have no idea how their support works or who does it. This is just based on other support calls I have made to various vendors.