The federal government wants to pass laws to rein in the growth of the $56 billion program, which will result in more than 100,000 participants being kicked off the scheme.
A Senate inquiry examining the reforms was also told the changes risked creating a "two-tiered" system that would make it more difficult for disadvantaged people to access services.
Darwin Community Legal Service chief executive Rachael Bowker said there was little safeguarding from oversight bodies in the NT and a raft of predatory practices occurring.
"We have Aboriginal people being taken advantage of, their plans drained and there is no one to stop that," she said.
Integrated DisAbility Action head Tania McInnes said there was a lot of phoenixing, in which discredited providers resumed business under different names.
"There are people moving people from one community to another without their permission," she said.
"We've got some of our most marginalised citizens being taken advantage (of) at a rate that is just breathtaking."
There were 17 NDIS staff on the ground in the NT, the inquiry was told.
Ms Bowker and Ms McInnes are part of a collective that supports the government's intention to address exploitative provider conduct but believe the current bill shouldn't pass.
Provisions in the bill assumed people were using metropolitan services and that participants were literate and digitally connected.
Those circumstances did not necessarily exist in the NT, they said.
The bill would also shift the burden of scheme sustainability onto people with a disability and assumes that safeguards existed when they were not in place across large parts of the territory.
Multiple legal groups told the inquiry the reforms shouldn't pass in their current form.
They raised a range of concerns, including around requirements for people with a disability to exhaust all "appropriate" treatment options to be eligible for the scheme.
"It risks creating a two-tiered system," Justice Connect's Samantha Sowerwine said.
"People with far greater resources will have access to the NDIS rather than the clients we see regularly through legal aid.
"The most structurally disadvantaged will struggle to access treatment even with the safeguards that have been added in."
The federal government was hoping to pass changes to the scheme through parliament before the July break but agreed to delay measures until at least August in a deal with the Greens to get tax laws over the line.
Labor is planning to increase fines for some NDIS-related offences, but a previous report warned stronger deterrents may be needed to crack down on exploitation, neglect and abuse of vulnerable Australians.
