Worse customer service ever!

I ordered a few things from Truworths online, paid for it and was awaiting delivery. Today I get a message to say my order was cancelled. I call them and was told that the prices on the website was incorrect. The prices that they put on the website themselves? How is that the customers problem? Upon taking my money for the order, does that not mean the accepted my order and will process as they advertised? How can they change the price a week later and then not honour the agreement with me? Their customer service desk is the worst, I was told that I should be grateful that they are crediting my account and that they can change prices whenever they want.