An Auckland driver's been issued a formal warning after kicking a commuter in the back, in retaliation for being punched in the head. 

Tramways Union president Gary Froggatt told Heather du Plessis-Allan NZ Bus's response is heavy-handed and unfair.  

Froggatt is planning to appeal the warning and preparing a personal grievance case on behalf of the driver. 

“It was a vicious, unprovoked assault, and what the driver was trying to do was get the passenger off the bus before he assaulted anyone else.” 

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