Unacceptable service

I went to the mr price store in golden acre mall . The transaction went smoothly until i got home and saw on the slip that the store email the cashier did not scan all the items and over charged me on one item . I then went to a another store in Cape gate to enquire because i tried to call the golden acre store but the call kept ringing and went to voice mail i then asked at cape gate and requested that they call the store because cape gate refused to then return and give any money back and once i spoke to the cashier she told me i must go back to the store bring my bank card and bank statement which i feel is unacceptable because i am leaving the country in 3 days and they bluntly refuse to assist not even co sidering if someone could pick up the money or even a deposit to be made so i must just be satisfied with a no and accept it . very unacceptable service