Dr Gaurav Sharma has been ordered to pull down a sign which advertises him as the MP for Hamilton West - a job he resigned from.
Dr Sharma's resignation triggered a by-election, in which the exiled former Labour MP is standing.
The sign is standing outside the office he used for electorate work while an MP.
The Labour logo which used to appear in the bottom left corner has been covered over with red.
Parliamentary Service chief executive Rafael Gonzalez-Montero told Newshub in a statement he'd asked Dr Sharma to remove the sign.
"Parliamentary Service is aware that Dr Gaurav Sharma has signage up where he refers to himself as the 'Member of Parliament for Hamilton West'," he said.
"After being made aware of this on Friday of this week, we wrote to Dr Sharma asking him to remove the signage as this descriptor is obviously incorrect.
"Parliamentary Service administers funding and services for members of Parliament, for parliamentary purposes. Since resigning from his seat, Dr Sharma is not entitled to parliamentary funding for a billboard or any other forms of publicity."
When Newshub approached Dr Sharma about it on Friday he was unaware of any order to remove the sign.
"I haven't heard anything personally, no," he said. "It is up to Parliamentary Service to sort it out."
Dr Sharma sent Newshub images of the hoardings he had been placing across Hamilton - which feature the logo of his yet-to-be-registered political party 'Momentum'.