First off, just because a dealer is listed on Mutoh's website does not mean they have a trained tech on staff. They could send anyone out and no one would be the wiser. Mutoh doesn't even have a list of trained techs so you wouldn't be able to verify anyway. I place warranty calls all the time and not once have I been asked if I was a trained tech before getting paid.
If you are under warranty, call the dealer and tell them to fix it. If they don't, call Mutoh and speak with Mike Bisson. He is the head of tech support at Mutoh and will strong arm the dealer or find someone else to take care of you.
If you are not under warranty, call the dealer and tell them to fix it. If they don't, call Mutoh and complain that the dealer's tech ruined your machine. They will normally contact the dealer and ask what's up and why is this customer calling us saying you are breaking their machines? The dealer usually will bend after that. If they can't or won't help you, it's up to you if you want to get into the legal stuff.
If the tech was not from a dealer/independent, it's all on you to chase them down and get your money back at least. And then post a scathing review online.
Long story short, Mutoh really doesn't like it when their dealers screw a customer on tech support on new and old machines and will put pressure on the dealer that caused the problem.