Telstra is expecting to have the last of 3500 Wollongong internet connections that went down on Saturday reconnected by Friday.
On Saturday, a large number of Telstra customers in the CBD and surrounding areas lost their internet and phone services due to flooding in the Wollongong exchange.
Telstra area general manager Mike Marom said the flooding occurred due to the heavy storms during the past week.
"Water came in through the roof and then we had some issues with drainage and downpipes," Mr Marom said.
A leaking pipe on an airconditioning unit also contributed to the problem.
Mr Marom said about 3500 ADSL connections and 1400 fixed line services were damaged.
By Wednesday morning he expected all the fixed-line services to be repaired.
As for the ADSL services, Mr Marom said about 1100 had been restored by midday on Tuesday and a mobile exchange was installed on Tuesday night to alleviate the issue while repair work continued.
He said he expected work on the last of the remaining 2465 services to be completed by the end of the week.
"At this stage we would anticipate as a worst equation that all services will be up and running by Friday," Mr Marom said.
Harvest Market fruit shop in Wollongong was one of many businesses affected.
Store manager Christina Sciacchitano said the internet and eftpos connections were online on Tuesday after four days down.
The business lost its connection on Saturday afternoon, prompting staff to inform customers that they could only accept cash or process credit cards via the old-fashioned manual transaction method - using a credit card machine and filling out a payment slip.
"We had to turn people away [on Saturday], we had to tell them to go to the closest ATM but they were closed down as well," Ms Sciacchitano said.
"At that point our sales dropped because people were quite cranky about having to go back and forwards from here to their bank and then back here again."
However, the mood of the customers - and their method of payment - changed from Sunday once word got around about the extent of the CBD internet outage.
"The majority of people are now coming in with cash, and they also know that we are trying our best."