"I told her it was public transport and the seat was allocated for prams."
Ms Bewley said she eventually felt she had no choice but to to get off and wait on the cold, dark Lower Hutt street for the next bus to arrive.
When she boarded the next bus bound for Wainuiomata she told a fellow passenger what had happened, who then informed the driver.
The driver dropped Ms Bewley and her son at their home in Wainuiomata and told her to lay a complaint against the driver.
She laid a complaint with the NZ Bus the following day.
NZ Bus southern region chief operating officer Tonia Haskill said the bus driver in question had not been at work since Wednesday.
Ms Haskill said she could not comment as to whether or not the driver had been stood down as a result of the complaint.
An investigation would take place on Monday, and the company would speak to the driver, as well as approach witnesses and review any CCTV footage that might be available.
Ms Haskill said a bus driver could ask a passenger to fold down a pram at their own discretion.
"It depends on the bus, if there is a wheelchair space on the bus not occupied by a wheelchair then a pram can be brought on unfolded."
Ms Haskill offered her apologies to Ms Brewer and her son.
"This is obviously not the kind of experience we want people to have on our buses."
Ms Bewley said she had not received a personal apology from NZ Bus.
"[I hope] they apologise in person, or even over a phone call or something."
Kevin O'Sullivan from the New Zealand Tramways and Public Transport Union said a union representative would be attending a meeting with the driver in question next week.
"The company are going to investigate the complaint," he said.