Dun dream meaning is explained below using 3 different sources. Each interpretation is shown with its source.

Interpretation 1 — Stearn Robinson - Tom Corbett

A dream of contrary. Being dunned for pay- ment in your dream por- tends an unexpected large profit or increase in in- come, unless you actually are in a financial mess, in which case the dream is simply asserting a threat to your mental welfare and you should try to work out a sensible plan with your creditors.
Source: The Complete Guide to Interpreting Your Dreams Author: Stearn Robinson - Tom Corbett

Interpretation 2 — Gustavus Hindman Miller

To dream that you receive a dun, warns you to look after your affairs and correct all tendency towards neglect of business and love.
Source: Ten Thousand Dream Interpretation Author: Gustavus Hindman Miller

Interpretation 3 — Internet Archive - Anonymous

To dream of being Dunned for payment presages financial success.
Source: Mystic Dream Book Author: Internet Archive - Anonymous