More than 150 bus drivers working for Metroline at the Potters Bar garage in London have voted for industrial action.
The drivers are sick of what they describe as mistreatment by managers.
Unite union reps on Sovereign buses in Edgware, London, are in further talks with management after drivers rejected a pay offer by nearly 90 percent. Bosses offered a 2 percent increase for the first year of the deal, and a 3.2 percent increase in the second.
But the deal will mean worse pay for new starters for two years, and probation will be extended to one year.