Edgars needs to employ people that can read!

My mum is 67 years old. She has an Edgars account. For a while now she has limited sight and many health issues, so I have taken over paying her monthly installments. My habit is to go into the store ask the amount of the installment and round it off and pay it. I have done this throughout. Last month my mum went in and they told her there is an amount in arrears of R200+. Her installment is around R350. So she paid R600. Might have been a balance of +-R50. When i went in yesterday to query and settle i am told that installment is R357 and amount overdue is R655. How is it possible to jump from just under a R100 overdue to R655 in a months time. This is beside the monthy installment. How is a pensioner with no other source of income suppose to pay R1000 a month on a R3000 account that doesn't go down? I called the contact centre and the lady an Andisa or Andiswa had terrible customer service. Her response was we need to pay it. No help at all. Can't explain me anything besides what I can see for myself on the slip. What point is having a customer care line if the customer cannot be helped. Is this the type of business a big comoany such as Edcon strives to be? A ****** of the poor? How can an account be in arrears if people go every month with out fail to the desk to query and give the amount that is due. This is all just a **** to take advantage of the elderly. How is it our fault if your employees can't read a computer screen and give the correct amount that is due? I am very unhappy about this and if it is not satisfactorily settled soon, I will be taking this further.