That truly sucks, and situations like yours are the first thing that came to mind when I saw that post with the message from the CEO, promising to do better. Plenty of opportunities to do better.
I haven't needed any customer support on my ST2 in a year and a half, but always had stellar experiences. Had to wait a long time to get the rear basket but haven't needed any replacement parts.
You should make a written record of your attempts to get a new controller if you haven't already - might come in handy to eventually pound one out of them at no charge. Alternatively, I don't know if aftermarket controller upgrades are available for the City, but you might want to check with Area13 and ElectroBikeWorld to see what they might have to offer (they sell essentially identical 35A controllers for various Rad models, I put one on my Mini and it's a much-stronger bike now for $225).
Good luck and if you think of it, please come back to update; lots of us are curious about the Rad customer experience these days.