You could write them a letter headed "Change of Address" and explaining what it ought to be corrected to.Same company that reads the postcode WF9 as WF19. An error that has caused us many, many missed and late deliveries.
They doubtless employ someone part of whose job is to change or correct addresses.
If you feel like it you could photocopy your letter and send a copy back with a copy of theirs every time you get a wrongly-addressed letter or delivery note.
If you don't tell them, how will they know?