Did they seriously sell a Gem 'New Relic' as a diagnostic tool that flat-out makes up queuing and response latency numbers on requests to their platform? If this is true then hell yes they need to refund all their customers!
New Relic is a third party tool that Heroku resells. The numbers aren't made up; they are measured, but in the wrong place. The result is still wrong numbers, but it's not obvious where to pin the blame.