I didn't receive any help your workers are not fully informed about the system

I didn't receive any help your workers are not fully informed about the system. I want to change my plan and I'm forced to pay 1rand so I get sim cards. When I explain there is no money in my account because I jst paid I will pay month end when the plan is changed I pay that 1rand I'm told is not possible. How is that if I'm paying at the end. I'm using the R739 plan want to change to R559 plan I'm denied to do so end of August I want my plan changed but no they won't I have to change it AGAIN end of August and I'll have to pay R739 which I can't afford. I don't understand