Complex sentence: The FBU demanded a 39 percent increase in pay, which would have brought the average firefighter's wage (at the time) to around £30,000, it balloted its members for a strike in late 2002, the industrial action began in November.
Split into simpler sentences: The FBU demanded a 39 percent increase in pay, which would have brought the average firefighter's wage (at the time) to around £30,000. It balloted its members for a strike in late 2002 and the industrial action began in November.