The Telecommunications Users Association says the latest fault with Telecom's broadband service highlights design problems in the network.
Broadband services to up to 10,000 Telecom customers were cut for at least two days due to a Wellington-based fault. The company said services were restored on Tuesday night.
According to Telecom the problem started at 8am on Monday, but some customers said it had been happening since Saturday.
Telecommunications Users Association chairman Chris O'Connell said Telecom's slow response shows it has no plan for when things go wrong.
If it wants to improve its service, he said, it needs to work with other broadband providers, instead of fighting them.
Mr O'Connell said that if nothing is done, the current problems will only get worse as the demand for broadband increases. "This is a sign of what's to come," he said.
Centred in Wellington, the fault - which Telecom says relates to a piece of equipment known as a RAN or remote access node - and caused problems for customers in both the North and South Islands.
Telecom will assess compensation for affected customers on a case-by-case basis.
Dial-up, mobile broadband and landline users have not been affected.