letter copies
This is one of the things Sue needs reminding of. I insist that any important letters have copies taken before anything else. If they need returning for whatever reason you still have a reference to go back to.
Ok when any issue is over and done with then possibly then discard the copy. You should see my box file on camera and computer correspondence it is full and now filling up the next one.
I don't rely on copies on a computer but always do a print out hard copy. This has often save any disputes that may arise.