Raffaele Marciello says the GruppeM Mercedes squad had a Bathurst 12 Hour win "stolen" by race officials, and that it was "treated differently" to Australian crews as an overseas team.
The car served two drivethrough penalties during the race, the first coming when Maximilian Buhk was stung for weaving behind the safety car on a restart midway through the race.
The #999 Mercedes-AMG GT3 was then forced to visit the pits again when Marciello was penalised for passing under yellows.
Marciello claimed neither were legitimate penalties and directly contributed to the car finishing third.
"We had a victory stolen," he told Autosport.
"We got two drivethroughs that... don't exist. It's impossible to get a drivethrough like that.
"When they say I overtook under yellow, the yellow was behind me. So that's strange.
"Then Maxi [Buhk] got a drivethrough for weaving. A lot of things happened.
"We had to win, we didn't win, so we can't be happy with a P3."
The #888 Mercedes run by Brisbane-based Supercars squad Triple Eight was also penalised for a safety-car infringement, but team boss Roland Dane was able to successfully argue the decision with race officials and have it overturned.
Marciello said GruppeM was not given the opportunity to plead its case for a reversal.
"I don't want to blame or complain, but the #888 got a drivethrough, they were able to argue and somehow they removed the drivethrough," he said.
"We got this drivethrough, we wanted to speak to the marshal to explain what happened, and they didn't even listen to us.
"We got treated differently [to] the Australian drivers.
"That's a pity. It's a great weekend, so I think they should change the mind of the Australian people to be a bit more open."