Alexander complained to Howick and Eastern Buses, New Zealand Transport Agency and the Minister of Transport Gerry Brownlee.
Howick and Eastern Buses general manager Sheryll Otway confirmed they hired security guards for some of their Saturday night buses four weeks ago and installed CCTV cameras.
It is illegal to consume alcohol on public transport and could lead to a $300 fine.
However, when the Herald on Sunday took a bus into the city on Friday night, a group of young men and women were flouting the law and were unrepentant.
About 10 people, mostly males aged between 18 and 21 who had been at a 21st, sat at the back of the bus with open beer bottles, sometimes yelling obscenities at other passengers.
Passenger Oryn Cockroft, 18, said he didn't believe it was a problem. "The bus driver doesn't mind so why should we stop?" Cockroft said.
Another drinking passenger, wanting only to be known as Tyler, said he did not know it was illegal to consume alcohol on public transport.
Bus driver Michael Mani said it was a quiet night compared to Saturday nights, before doing a routine check of the bus for broken bottles.
"What can we do? They have bottles in their pockets and I tell them to take their bottles, but they drop them and they roll around all over the bus.
"This is a quiet night, sometimes they are smoking and some passengers have said it smells of urine."
Another passenger, Tania, who was with the same rowdy group, disagreed with her friends. "I think they should shut up and respect the people up the front ... there is no need to be obnoxious twerps," she said.