Green Party MP Jan Logie said 11 of 18 sexual violence support providers surveyed reported a significant increase in demand.
"Every time we have stories in the media, it triggers people to go and get help. That's a really good thing but the problem is that our current services were already struggling, and Government knows that."
She said the Government should be more pro-active in its support.
Wellington Rape Crisis manager Natalie Gousmett said existing and new clients had sought extra support from the organisation.
Although the surge corresponded with an increase in public donations to the service, there had been no increase in Government funding.
The organisation received $77,000 from the Ministry of Social Development, and $233,000 from fundraising and grants.
The police investigation into the Roast Busters case is ongoing.
Detective Inspector Karyn Malthus said: "The focus remains on speaking with a number of girls, a process that is incredibly delicate and requires a great deal of care and time to ensure the health, well-being and privacy of the girls is maintained."