An even temper, good manners and careful record keeping can help defeat call centres that don't co-operate.
Contact Centre Institute chairwoman Nadene Gavigan said people encountering a call centre needed to apply courtesy and an even temper.
"There are some very rude people who want to take their frustration out on the person who answered the phone. Just remember the person that you're ringing is not necessarily the person that got them frustrated in the first place."
Fair Go's Gordon Harcourt said polite insistence was essential. "They are human beings," he said.
He said if it didn't work, asking to "escalate" the issue "seemed to push a button" by getting more senior staff on the phone.