The CSA1 and CSA3 jobs are for the Ground Handling Services section. The flight planners jobs are in the Operations Control, Flight Support Department.
The CSA1 job is basically a check-in agent.
The CSA3 job is a CSA1 and a Traffic Agent combined.
(There is also a CSA2 grade which is a CSA1 and ticket desk combined but I think these positions may be filled for the summer)
I believe they are still looking for seasonal full and part-time CSA1 and CSA3's for the summer.
As for the Flight Planners in the Flight Support/Operations Department i'm not to sure.