They're going to ask you how you would deal with an irate customer. Tell them you would say you understood their problem and explain the situation to them politely. If they don't like the policy, you'd politely ask them if they would like to speak with a manager further about the problem.
I worked as a inbound telephone sales rep for DR power equipment/country home products...aside from not aggressively selling all the 'upsells' to people who didn't need them, I was very good at my job. The position often involved a lot of customer service and technical support, if you wanted it. I wasn't to bad at it even though I have very little understanding of small engines.
Some of my colleques were terrible though, they'd transfer anyone who was trying to buy a replacement belt to the technical que which usually had about an hour wait. Retarded since I sold the same kind of belt almost every other call, and those people either hung up or were seriously irate when they finally got through. The training was kind of bad though, they just taught you about some of the products but when you were out on the floor I spent most of my time with technical manuals that they'd never even showed me before.
Telephone customer service is kind of weird, I'm surprised I was cut out for it...but it was easy, air conditioned and paid better than any of my other prospects in addition to having a set schedule that I liked.