Always send lens AND body when having focus calibration issues, as both are involved. If the lens is calibrated to front-focus, and the body back-focuses, the result will be correct focus. But when you put the lens on a correctly-calibrated body, you'll get front-focus. The problem might be the lens you didn't send in, and not the 1Ds.
thanks for replying. Yeah, I think I will bring both for them when I return to HK.