dun for
dun (someone) for (something)
To nag or bother someone to pay money owed. Don't answer the phone—creditors keep dunning me for money that I just don't have right now.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
dun someone for something
to harass someone to pay a bill or deliver something. If you don't pay the bill, they will dun you for it day and night. My job is to dun people for payment of their bills.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.