Here are some podcasts you can listen for vocabulary and advice on complaints, both as a customer (making a complaint) and as a supplier (handling a complaint.
In relation to our class on "Confrontations and Conflict" in the workplace, here are some ESL podcasts on dealing with conflict, dissatisfaction and disagreement.
Business English Pod - Resolving Conflict
Some vocabulary you will hear in Part 1:
Some vocabulary you'll hear in part 2:
G.A.L.E.S.L. / joe3
Some tips and links on learning English.