Mr Wishnowsky said the Kiwibank ATM at the front of the store was "absolutely cooked" and would be expensive to replace.
He was glad most mail had been unaffected, with the only damage found being to a couple of packages that had sat on the floor. "We ended up taking a couple of hundred litres of water on Saturday with a Rug Doctor and the cleaners went through on Sunday to soak up as much as they could."
Some systems were down yesterday morning, such as international postage and money orders, but Mr Wishnowsky hoped the store would be back at full capacity tomorrow.
Mount Mainstreet manager Leanne Brown said damage to shops had been "sporadic". Some of the worst-affected shops had neighbours that were untouched.
"A lot of the water came from the back of the stores so it depended what the foot steps were like at the back of the shop.
"Fortunately, a lot of the stores had polished concrete floors so it was just a matter of mopping up."
Ms Brown said shopkeepers had done their best to make sure they were open yesterday as it was now the school holidays.
"It will be a couple of days before we're back to normal but we're doing our best," said Ms Brown.