Jodie Landgren and Jodie Boots, owners of Bally Boutique and Beauty and Olde Vintage Charm respectively, both told the Courier that since the extensions to Stockland Baldivis opened, staff were parking all day in the car park designated for their businesses.
As a result, fewer people are visiting their stores and Mrs Landgren described the situation as "ridiculous".
"It's affecting our businesses as our customers can't park and unless they have a 4WD to park on the roadside or in the sand, they won't park on the rooftop (car park) just to come here," she said.
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READ NOW"There's a car park for our businesses and limited parking on Atwick Terrace, but other than that there's not enough parking.
"Even the new library doesn't have sufficient parking."
Both Mrs Landgren and Mrs Boots appealed to staff and those intending to shop at Stockland to park at the centre's new rooftop car park to "leave our bays for our customers".
"Our customers come (into the car park) but can't park because Stockland staff are parked there from 8am until 6pm," Mrs Boots said.
"I've tried leaving notes to let them know, but they don't care because they keep coming back."
In response to the complaints, Stockland Baldivis centre manager Kathleen Brown said the centre manages its parking facilities and had been encouraging centre staff to park at the provided temporary staff car park.
"All retail staff have been directed to use the designated parking area, which includes designated bays within the permanent car park," she said.
"These areas are managed by the Stockland Baldivis team; we have also introduced a traffic control management team who are ensuring customers are directed to available car spaces and we also have courtesy staff on hand to guide people around the new multi-storey car park."
The centre will have 1350 available car bays when the second extension opens next week.
City of Rockingham is not able to enforce any penalties in the Atwick Terrace car park as it does not have jurisdiction because it is on privately owned land.