pension payout

i am a pensioner and this company is the one handling my pension pay out and i have tried to plead with them to give me my full amount for the last 3years now instead they tell me stories that i dont even understand i am very old and i cant survive with the little money they give me every month plus on top of that they taking taxes out of my pension and what i know is as a pensioner i dont have to pay tax,, i have grandchilren to look after and i cant live with R400 a month that they giving me, i just want my full pension money sothat i can also be able to do things that i wanna do.