"Adjustment complaints can be viewed as an opportunity to satisfy a customer who can be temporarily to dissatisfied and thereby make probable continued pleasant relations."

-- Business Correspondence, p. 23

• complaint letters -- request compensation for problems with purchases or services
• adjustment letters -- responses to complaint letters.

OK, so those definitions were clear., and Mr. Reyes was probably referring to an adjustment letter.  But I couldn't find the specific phrase "adjustment complaint" anywhere.