the only way you will have any certainty over the meaning of "di" which could well be dopo incasso, but could well be anything, is to speak to the actual author or somebody who does precisely the same back office banking job. Unfortunately the back office jargon doesn't get onto the Internet much, but tends to stay in the back office. The agency probably won't want to "bother" the client to that extent and probably won't allow you to either, so you might just as well guess.
This google of "resi di marcatura" demonstrates what a closed and secretive language back office banking jargon is.
https://www.google.it/search?source=ig&hl=it&rlz=&=&q="resi ...