Sir, I understand that you may be acquaintances with the owners and that they may very well be wonderful people. Their social pleasantness doesn't change the fact that their business policies are ridiculous. Frankly, and I sincerely apologize if this offends you, but such a blatant third party "attaboy" for My Plumber just feels suspiciously like a paid shill attempting to do damage control. To be even more honest, I've had several weeks of perfectly hot showers to almost forget about the incident and this comment has only served to rekindle the flames of anger that I felt when my wife told me the result of the "diagnosis."
Again, I hope the best for your friends in life, but people need to be and will continue to be told about My Plumber's business practices before they get burned. And again, sorry if I offended you.