Keira MP Ryan Park has concerns the government won't consider feedback from South Coast rail commuters on the new timetable when it is reviewed later this year.
When the government introduced its revamped timetable in October last year, Transport Minister Gladys Berejiklian promised a review in 12 months.
Mr Park said it was important the region's voice was heard on the issue if the government wanted to encourage people to keep using public transport.
"It is clear that customer needs are not being met, in fact the commuters are so unhappy many are even turning to their cars and driving to Sydney," Mr Park said.
"We should be looking at ways to encourage people to use public transport not forcing them away from it."
However, Mrs Berejiklian rejected Mr Park's claims, saying the government reviewed timetable-related feedback "from all parties".