When vacating the client's guilty pleas, Judge David McNaughton said there had been a "substantial" miscarriage of justice in the case.
While Arman was acting in the case, there were a series of court appearances but Arman was often represented by an agent, or not at all on three occasions, the tribunal said.
He also failed to maintain proper written records of his instructions to agents and also lost the client's file.
The tribunal said Arman further did not meet or discuss trial strategy with his client, whom he told had no chance of successfully defending the charges.
He also advised him wrongly of the likely sentencing outcomes.
The tribunal added Arman had been absent at his penalty hearing and had failed to demonstrate insight or remorse for his conduct.
Arman was also ordered by the tribunal to pay costs of $16,024.
It is understood Arman no longer lives in New Zealand.