Jup, I did that. + I wrote that I play only in drop C in the letter where I described these problems.Just to confirm, have YOU adjusted the intonation for drop C? I want to make sure you weren't sending it out to get set up and the people doing the setup were adjusting it to standard tuning.
What happens when you adjust the saddles back and forth for intonation? Are you running out of room?
Don`t remember, I think that room was enough. I adjusted intonation to 0th fret, 12th and 17th. The biggest problems were on 1th,7th,10th...