Pathetic service from FNB life

I am very very unhappy from FNB life , I have life policy from them and last 6 months they have been deducting money from me but lately they start to deduct extra money which I am unaware of , I phoned the call center they told me that the system some time does that ? How come it is possible?This is cheating and unacceptable by me . I am very very unhappy about all this .and this dodnt happned once it's more then 3 or 4 times last 3 or 4 months.