The automotive repair store in Manukau is reliant on customers booking its services on the phone and has received no new business since yesterday morning, Mr Walden said.
"We're losing money while it's down, that's for real. It'll be starting to mount, I would think.
"Obviously we're not getting any work at the moment, we've just got leftover jobs we're finishing off which is lucky we've got a few.
"I think most small businesses are on the bread line as it is these days. We're just getting by, no more. We don't need this at the moment."
He said he asked for the calls to be diverted to his cellphone but the company said it was not doable.
It was a similar story for Victoria Park Flowers owner Amanda Browne, whose landline issues were fixed just before 1pm today after more than a day's outage.
Ms Browne was tearful when she told NZME News Service she didn't want to think about the prospect of the business going without a phone line for much longer.
She said about 70 per cent of the flower shop's business came via calls and she estimates she lost about $600 of business in the last day.
"I just feel so stressed.
"It's just whether I've lost [the business], or not. Nobody's actually emailing to say 'I can't get through' so I don't actually know."
A real bugbear was the lack of communication from the company, she said.
Ms Browne only heard about the phone outage hours after it had started because she got a call from her courier company saying they couldn't get through.
She said Woosh should also be held accountable because bills were still being paid to the provider until early September.
"I just wish they'd communicate it. The people I've talked to have been really good, in terms of being patient, but they just don't know anything.
"I received no notification from Slingshot at all. I got one email from Woosh saying 'We've been sold' and that's it."
M2 New Zealand consumer general manager Taryn Hamilton said Slingshot had been "migrating" Woosh customers onto its network in the last few weeks.
He said there were about 100 phone line customers currently impacted, most of whom were residential.
"We have been working to get everyone back up and running, and hope to have everyone back online soon," he said.
Slingshot had communicated the issue on its hold message and was in the process of sending out an email update and apology, he said.
"Customers understandably get upset when we can't give a firm time on when the problem will be fixed," he said.
Meanwhile, other frustrated customers have vented their anger on social media, saying the customer service from Slingshot had been "awful".
Customer Sarah Wilson wrote on the company's Facebook site: "What the hell is going on? This is an office, and I can't work.
"You guys are incredibly unprofessional. In addition your option to press 'star' for callback does not work either. Does anything work?"
