Depending on your Skier Type (I, II, III or III+), weight, height, age and BSL, while the system may release reliably at the DIN setting, the manufacturer may consider these out of the acceptable range. Basically, IIRC, if the release setting DIN varies by more than two rows up or down from the initial setting, they are considered not acceptable. I need to check a binding manual for the exact description of the conditions to be certain.
One 'solution' to getting the DIN set in the acceptable range is to use a dish soap solution to increase the slippery-ness of the boot / binding interface. It is also possible that the AFD height is not correct or that damage or dirt on the toe lug and/or the binding is causing too much friction. Finally, the binding may in fact be defective. If you provide me with the Skier Type, weight, height, age and BSL, I would be happy to look it up.
A difference of 3 of the DIN could be OK or it could be too much for the manufacturer. It is not uncommon to have to adjust up or down 1 or 2 but 3 is pretty excessive. The difference between two rows is not consistent, hence the need to know the Skier Type, weight, height, age and BSL. If I were the tech, I'd look hard for other factors, especially on a new binding. BTW, how old is the boot? What is its condition?