ok then no he didn't, however he genuinely tried to be of some assistance. How about just saying something like "thanks, that's ok I will deal with the cost, now does anyone know about how do do the wiring?"
I have also done it before where someone has asked to do something and I often give them a different answer than what their asking, however it still proved to be useful to them. We have no negative intentions, are not trying to tell you not to do it so there is no need for the harsh resposes.