Proofing process - outsourced digital prints

A while ago I decided to try out some labs to produce digital prints, output to both Lightjet and 9600. I've had a problem with one lab that is starting to rankle, but would like to find out how the proofing process has worked for people at different labs.

To test the limits of the digital process, I had some small cloning done to a print. On the next proof, I could see this editing was just what I wanted. I gave instructions for other changes to the print, and the next proof duly arrived with these new changes - but no longer showing the previous set of changes. I was worried they'd somehow been deleted, so asked what happened. I was told "the changes you requested on your images have been retained...I apologize for the confusion created by sending proofs without the corrections you indicated...I assure you that the new set of proofs will contain your earlier instructions". And the next proof did. I then said the image was 'finished', and requested proof prints on a couple of different pieces of paper, so I could see the effect the paper had. These prints arrived, but with the editing work from a couple of proofs ago again missing.

On a similar issue, having said I was just about happy with another image, which just needed a slight overall darkening, I also received prints with this image on a couple of different types of paper. I noticed a mark on one side of the image, a mark which I thought wasn't on the film (I hadn't seen it on any earlier proof). When I asked about it, I was told it was on the film (correct) and that "this is a proof and we don't always take the time to meticulously clone out all dust and or distracting marks each time we make a proof. It must have been cloned out on previous proofs but not on this one."

For both, I was told all cloning and other changes will appear in the final print/s.
I didn't understand this - I assumed each proof would show the cumulative work on a print, not just each stage of the proofing process. I thought I could line up all my proofs afterwards alongside the final print, and see the proofing process show how the final print was achieved, but in fact this wouldn't work. And the idea that 'dust and or distracting marks' are cloned out each time a proof is prepared rather than just at the beginning, seems bizarre to me - not only does it seem to duplicate the printers work, but it means that just as I think I'm about to see the final print on preferred paper, I get a surprise by seeing problems with it that I'd never seen before.

Is there something about the process of creating a digital print that I'm not understanding, that results in these problems? Is it unreasonable of me to expect each proof to be the cumulation of all previous changes? I feel uncomfortable commenting on or approving a print that isn't the way I expected it to look, despite reassurances from the lab.

Sounds to me like they have issues tracking changes and versions (especially a problem when they don't match the proof you signed off on for the final)... I'd look around for a more detail oriented, professional retouching crew.

If you are not comfortable with the proofs and have confidence in the people you are working with... reassurances will be pretty hollow over time.

I would make small prints on a tabletop printer from your final photoshop image. Send the file to them and deliver the small print with your signature on it.

Your instructions are for them to match it.

The signature is important so they don`t just make a new sample. I had this happen with some custom cabinets and my mother with refinishing furnature. They actually had the nerve to change the samples to match what they did (different establishments). What they did not know I retained half the original sample with half my signature on the back side. I gave them them another quarter after I sawed it in half. They got to try again. It matched. It would not have been so bad had I not told them what stain to use and where to get it.

I'm moving in that direction, Will.

To clarify, all work on the transparencies was done by the firm - all scanning and photoshop work.