done, dun

Done or done is the past participle of "do", meaning to perform or execute--I do, I did, I have done--
Have you done your homework?
We have done this before.
Done or done may mean finished or over--
That was a lot of homework. Are you done?
The washing is done.
Done may mean ready--
Are the steaks done? Did you check them?

Dun or dun ( rhymes with done ) means to press for payment of a bill or debt--
He has to dun people by phone for his new job.
No creditor may dun you by calling late at night, or by calling too often.

Now that you know that, you can say--
"Before he was done with the call, he promised not to dun them again."

Note--"dun" also means a grayish-brown color, said particularly of a horse or a cow--
The old dun cow hasn't come home yet. I hope she isn't lost.