Baimed Physiotherapy and Sports Injury clinic owner Michael Baines spent at least 13 hours on the phone to Telstra last week, in a desperate attempt to get his Wollongong clinic's internet reconnected.
For the small business owner, the nearly week-long loss of internet and phone services at the Auburn Street clinic proved significant.
He was forced to pay hundreds of dollars in extra wages to resolve accounting problems arising from the fault.
Although his internet service was restored at 5.50pm on Friday, Mr Baines believes the fault's impact will be felt for months.
"It's going to take us a good 12 weeks to chase all the accounts," he said.
"I've had to pay extra wages to try and sort it out - I've paid at least 40 to 60 extra hours across the three clinics so it's definitely not insignificant; there will be a loss to our cash flow, it will have a flow-on effect."
Telstra told the Mercury on Monday that some customers might still be affected by the fault, despite work on the Wollongong exchange being completed over the weekend.
On March 29, flooding, stemming from heavy rain earlier in the week, caused the outage of 3500 ADSL connections and 1400 fixed line services.
Telstra began repairing the network that night.
A spokeswoman on Monday confirmed the work was now finished but said there "may still be some customers experiencing issues".
"We are currently working through call-backs to customers who have reported a fault to ensure their services are connected or to understand what needs to be done to restore their services," she said.
Mr Baines said Telstra's response was not good enough, expressing his frustration at the lack of communication.
"There just didn't seem to be any process in place to fix the problem," he said.
"There was no response from Telstra - at no point did you get to talk to someone about what was happening and why.
"The difficulty for us is trying to quantify the sheer manpower needed to solve the ongoing problems [from this] and having to pay staff to do work they normally wouldn't have to do."
Telstra area general manager Mike Marom said there was a process in place where businesses could claim lost money due to the outage.