This is not original advice--but is it effective!

When presented with a problem, try to put yourself and the other party on the same side. How? Simple: Request the other person's help. If you're not sure how to do that, try asking, "How can we solve this?"

Recently, I employed this technique when my former bank--let's call it "Constrictor Co"--helped itself to a number of little gifts from my account.

"How can we solve this?" I asked the rep. No need for shouts, threats or abuse. There never is.

Happily, Constrictor hires polite and accommodating staff to care for its victims. Whether the problem will continue, I'll know in three to five business days. In the meantime, it doesn't hurt to start from a position of politeness and the assumption (stated, if not heartfelt) that the situation was caused by a genuine mistake, rather than malevolence. (Not always an easy assumption, but still.)