Bad customer service

My sister was handed over by foschini because she couldn’t pay her monthly instalments due to financial difficulties. She then arranged a payment option with them now she is done she paid up her account, when she calls they say it doesn’t reflect she kept on calling the consultant said the payment will be cleared after 6 weeks so obviously if she wants to apply for a loan she won’t be able to because of this, she can’t wait for 6 weeks that’s nonsensical.