There is a saying that goes way back; "The message sent was the message received", the sender is always responsible that the receiver understood the instructions correctly.
Not taking any position here, however when trying to understand why things went bad, always first look in the mirror. After that recovery is the next step and negotiation will go the furthest when coming to a resolution. IMHO
C'mon man.
There was a piece of tape with a line drawn on it, and instructions to cut at the line. How much more clear could the OP be?
