Then its all on him. How can he say its not his fault if he did all the coordination under his guidance.

Its like when I ask my mechanic to fix something. He sometimes has to buy parts from a BMW dealer, have a tire shop balance/mount tires, etc. to do repairs. He depends on others but its all under his responsibility. If the tire guys screw up he doesn't come to me and say "well, I didn't actually screwup, the tire guys did, so you have to pay extra". He'll go to the tire guys and resolve it between them - nothing to do with me.

AND you have another thing on him - he got the wrong DME in the first place. So anything related to something being wrong is all on him as if he had the correct DME it wouldn't be coded incorrectly in the first place. LOL!