Accounts administrator Svenja Thornber said when Mr Hamilton raised the alarm on Tuesday morning staff went out to investigate.
"We called the fire brigade and then we called the SPCA, and then the drain people came and they put a camera down.
"They pushed it toward the exit but it didn't move any more so they thought it was stuck and they couldn't get it out."
Firefighters, the SPCA and drain specialists were involved in the rescue.
A plan was hatched to drill down through the concrete above the drain but permission from the landlord and Auckland Council would be needed.
Rescuers knew it was a race against time because it was unclear how long the cat had been down the drain.
The drain clearing company was called on Wednesday, and a crew headed by Mr Martin put a camera down the pipe.
It's thought Frog must have fallen from a roof into a downpipe and slid several storeys before becoming trapped underground, about 2m from the exit.
"He'd got so far down and the drain was so full of rubbish he couldn't get any further," Mr Martin said.
"When we pushed our drainage camera down and found him, we tried to push him out not realising there was so much dirt and rubbish in the drain."
Frog rewarded his rescuers with a few cuddles before being reunited with his caretaker.
The crew used a high pressure water jet to flush the rubbish out, taking care not to drown Frog.
"We marked him with the camera where he was in the drain. We measured the hose and marked that so we would stop about 200mm away from him.
"I took my T-shirt off and put some knots on the corners and put it at the bottom of the cesspit like a sling because it was 1500 [mm] deep where it exited."
With the camera Mr Martin gave Frog a push and "sure enough he poked his head out and sat in the sling".
"He was very happy."
Frog was collected by a grateful man who told the rescuers the cat disappeared while he was looking after the pet for two weeks for his daughter.