I'd ask for the head honcho if I were you!
I believe that I deal with the same tax office as Cuchulainn, and was told that the "head honcho" does not take phone calls from the public. I have been talking to various staff there, over the past 2 years, trying to get an issue resloved. Some of the staff agree with my theory, but seem unwilling to do anything about it because " the computer calculates the tax this way."