If there is an EBA in place then the rates are generally set in conjunction with the union/employer and you should be getting pay increases as agreed. If there is no EBA and you are covered by an award then you should be paid the award rate based on the role you are doing.

I would get a copy of your PD and then address all of the things that you actually do on a day to day basis. Look at how these align with the award rates and put a case forward. If you have union representation you can always ask them for advice too.

If you are meant to be getting increases and you have been on the same salary since Oct 2010 the I would say you are overdue for an increase and that is definitely something that needs to be addressed. An increase in salary sacrifice is fine but you should also have a pay rise.