today I got the scans of my Lomography 400 roll, as you can see the quality of these is quite terrible. While I think it's not a lab error but it's how I handled this roll, I'm not quite sure about what might cause this. I stored this film on my refrigerator (I don't know the exact temperature) for around 2-3 months before I sent it and I'm not finishing the roll on the exact day I'm loading it on my camera. Then again, I've had rolls that I don't finish in one go before and stored it for quite some time but the results weren't like this.
Taking a while to finish the roll won't normally cause problems (within reason). I've finished rolls in the past year that sat in a camera for literally a dozen years and got acceptable images.
Part of what you see above is certainly a scanning issue -- the vertical (as shown) banding is probably due to a power supply ripple in the scanner or its scanning lamp.
The poor shadow detail is due to underexposure, pure and simple, and the green cast is from the scanning process trying to compensate for that. Not really a scanning fault, though it can be reduced by using scanner settings to let the clear film areas go black instead of trying to average the frame to a "normal" exposure.
I'd be very inclined to ask the lab to rescan this roll, and then use a different lab in the future.