dunning
dun-ning
noun
The act of persistently demanding payment for an overdue debt.
"The company's dunning process is automated."
verb
Persistently demanding payment of an overdue debt from someone.
"They are dunning him for the outstanding bill."
Thesaurus
Synonyms: dun, grayish brown, greyish brown, fawn, torment, frustrate, bedevil, crucify, rag, chromatic