Hi there - can you email me at pvh (at) heroku with a link to the ticket where you had a bad experience? This sounds like a bad UX bug that we need to fix, and I will make sure any unintended charges are taken care of.
I've also asked the PM for this project to look into what happened here and alerted the head of our support team. I hope you'll consider giving us a chance to make this right for you and a chance to re-earn your trust.