She contacted Intercity that day and was told she would get a full refund, and the two teens would be transferred to a later bus departing Tauranga at 9.10am.
She was told pair's bags would be waiting in Taupo, however when they weren't there, Ms Irvine was told they would be waiting at the Wellington bus depot.
She said a couple of her son's belongings on the bus were also "thrown out" by the bus driver.
"Then get told they have thrown out some of my sons items (his jumper and baseball cap) due to them having a bit of sick on them, they did not abandon these items, they were taken from them when the bus driver left them at the side of the road and took off."
She said she was "fobbed off" by an Intercity employee and was told there was "nothing more they can do".
"I am so angry and the lag (sic) of compassion from intercity is appalling," she wrote.
Mr Peate told the Herald there was a "miscommunication" between the two teenagers and the bus driver that day.
"We now know he and his friend had an expectation the bus was going to wait, however it didn't wait because that request wasn't made."
While Ms Irvine said her son had asked the bus driver if he could grab a change of clothing from the locker, Mr Peate said the driver "didn't recall" the conversation and this was verified by other passengers on the bus.
"They had just said they wanted to be let off the bus because one of them was sick."
He said the driver then saw the pair walk away.
However Mr Peate said the bus driver "should have clarified with the two passengers" if they had any luggage in the locker, rather than driving off.
When the bus stopped in Taupo, the driver cleaned out the vomit on the bus and found soiled clothing, he said.
"It was very soiled and she threw that out."
He said he had apologised to Ms Irvine and she would be compensated for her son's belongings that were thrown out and a refund was also given for both tickets.
Mr Peate said the teenage boy was a "frequent traveller" on Intercity buses and had "never had issues" before.
"He in fact travelled back to Tauranga with Intercity on Tuesday."
He said the company was currently in contact with the driver regarding the incident but couldn't comment further as it was an employment matter.