A "frustrated" pair trapped in a Wilson car-parking building smashed a ticket dispenser before ripping a barrier arm off and driving away.

Roi Wilson, 25, and his elder sister Akoia Atarangikahu Wilson, 33, had parked in a Wilson Parking facility on Christchurch's Hereford St on August 24 when they had trouble leaving.

While trying to drive out, the barrier arm remained down, Christchurch District Court heard today.

Roi phoned the parking building's call centre and abused the call-talker, demanding that they raise the barrier before he hung up.

He immediately phoned again and the call-taker explained to him that he'd have to apologise for his language and behaviour.

While her brother was on the phone, Akoia tried lifting the barrier arm.

When she failed, Roi punched the ticket dispenser, causing the front panel to shatter, according to the police summary of facts, which the siblings accepted in court today.

Akoia then lifted the barrier arm, breaking it off its bracket and throwing it to the ground.

They then drove off.

Today, the siblings admitted a charge of intentional damage.

They accepted they will have to pay reparation of $1514.75 for the damage caused.

Community Magistrate Leigh Langridge referred them for restorative justice to be considered ahead of sentencing on October 8.