Bothners N1 City Value Centre Store

Tried to order John Thompson Easiest Piano Course Part 1 using the online facility. Once I had paid my eye cught the fact that the order had been changed to course 2 even though I had selected the course 1 book. When I called the store to ask about the issue I was told by the assistant that I had made a mistake. It is hard to make a mistake on their website as everything is in large font. Nevertheless, I was told that they did not have any in stock. Why advertise the goods if you dont stock it and why claim that the customer 'made a mistake' I am NOT satisfied!