The union for SkyCity Casino workers says it raised concerns years ago when it restructured.
SkyCity's casino operator licenses could be temporarily suspended - over complaints about host responsibility.
Unite Union says the casino slashed supervisor numbers by nearly 40 percent in 2016.
National Director Mike Treen says it was up to them to ensure people didn't play too long.
"I think it's led directly to the problems they're facing today."
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