I agree that carbon should have been cleaned by this process. See attached photo of the engine parts after being dismantled at the dealer.
The original service shop owner maintains that this has never happened before. I also have learned, quite painfully, that they are crooks and that this service was unnecessary.
I’m leaning towards the service being performed incorrectly - not regulating the amount of cleaner going into the engine per the manual I’m still trying to obtain. I just need to prove it. Crooks or honest mistake - I want to understand what happened.
Thanks for the input.