Which section of the road code says you can overtake a car using a bus lane? Because this doesn't say it's allowed.

When can you drive in a bus lane?

You can drive in a bus lane if:

the bus lane is only active between certain times and it’s outside those times

you are driving a vehicle allowed in the bus lane (e.g. motorbikes can ride in standard bus lanes)

you are driving an emergency vehicle such as a police car, ambulance or fire engine and you are responding to an emergency with lights and or sirens operating

you are making a left turn to enter a driveway or side street, in which case you can drive in the bus lane for up to 50 metres

the road is blocked due to an accident or road works

you are driving a wide vehicle and you need to use the bus lane because your load is wider than one lane.

a person is signalling to turn right and is either slowing down or stopping and you wish to overtake them on the left (note: the existing legislation has not had the amendment applied).

If you are turning out of a driveway or side street, or you are turning right into a side street then you can cross a bus lane.

You can’t park in a bus lane.

source: https://www.drivingtests.co.nz/resources/bus-lane-rules/

Just take the loss and move on with your life.