Querry about grant payments at banks

I was trying all avenues to contact someone at Capitec bank 're my complaint with no success. I'm a state pensioner I check at the bank if money was paid in I get positive balance. Next I try to draw the money and to my surprise I get the following reply " insufficient funds". As pensioners we find very difficult to get our grants. Nobody is prepared to help us . Supermarkets always paid but now on the 1st of month notices go up we haven't got cash available. So where do we go. My name is Gwen Coetzee.