The latest heist happened last Friday when four more speakers stolen.
"It's been a nightmare," said Mrs Maihi.
"We even drilled through the wall and put a metal plate inside the building thinking they would be secure because they were cutting them and pulling them.
"We came back after a weekend to find one had been wrenched off the wall and the whole side of the wall had come away."
She said after the first 15 speakers were stolen the school installed metal cages to protect them.
"But then they came along a couple of weeks later and chopped the cages off and took another four so we bought heavy-duty cages."
CCTV footage showed the thieves using a school bicycle stand to lever off a cage.
"It's getting beyond a joke and you see adults riding around on bikes with speakers on but you can't say, 'that's my speaker',"she said.
An exasperated Mrs Maihi hoped the release of CCTV footage would help identify the culprits and put an end to the school's woes.
She said the sound system was vital for communicating across the large school and it was causing major disruption for children at the 1000-plus pupil school who could not hear the bell for classes and other announcements.
Counties Manukau police Inspector Bruce O'Brien said police had noticed the new fad of cyclists strapping speakers to their bikes.
"It's hard to say they're the ones responsible for Finlayson Park but that's a bit of a trend we've seen in the last six months."
He said police were seeking the public's help to try and identify the two men in the CCTV footage.
If you have information phone 09 261 1300 or call Crimestoppers anonymously on 0800 555 111 or contact Counties Manukau police via Facebook.
