How to get support for my Ultra?

ROKU customer support can't explain how to return an unstable ROKU Ultra in three calls and over 45 minutes.  They don't offer an address to mail to. Is the Ultra just so bad you can't keep up?  One of the 4 calls just disconnected after a 10+ minute hold.  One call couldn't be forwarded because my current info didn't match the first of second ROKU i purchased years ago. One call gave me bad info, and  one call took another 10 minutes to tell me the previous call was wrong. Is there a path to reach an empowered competent CS rep?