Pricing error

Mango online store have advertised items ranging from R1 to R9, a gross negligence on their behalf? Or a demeaning sales gimmick to lure people to waste time selecting items randomly and revealing their credit card details on their 'secure' website? After receiving an invoice to thank me for my purchases and then receiving an email the following day to inform me that my money will be refunded, is really weak service/****. Mango need to honour the purchases made as do all major online stores who make similar errors. Why do we as the customers have to pay the brunt for your error?