Deducting money from my account

Good evening I would like to understand from nedbank why the small amount are vanishing almost a week,i did call the call center the was helping me told me the R1 and R2 are being deducted because im buying airtime which was not true,i check my account almost everyday,please let it stop,I left R90 now when I check i see R70 which I don't understand,I love nedbank I won't change it,please stop taking money from my account thank you...