I accidentally shot a roll of Fujifilm Superia ISO 800 as ISO 400 (forgot to resetset the dial, my camera is 100% manual ) so now all of the frames are (equally) overexposed. Is it possible to push-process the film to ISO 400 without any major compromises to print quality? (I'm very concerned about this specific roll because it contains pictures from sunset at Stonehenge, and as such is irreplacable.) Also, as I do not have a darkroom I would be have to get the film developed at a photo-processing service. Do many photo-processing services provide optional push-processing? Or is there some sort of mail-in service that could do a better job? Many thanks to anyone with advice.