Unsatisfied

I purchased an item online via truworths website, product was in stock in the chosen size. Everything was successful , payment made. Received a confirmation email . Two days later i receive an email stating my order was cancelled due to no inventory. However i went back to their website and the item is still available in the size they claimed to no longer have but the price has now changed. How is this the consumers fault? Called there online customer services and both Anastacia and Nicole were of no assistance and could not offer any sort of remediation. Is online not supposed to be more convenient?Are the staff dealing with online queries or any queries given training firstly on how to communicate with clients and on any legislation that is linked to consumers and suppliers? Consumers dont want to be inconvenienced of they have chosen an option which promotes convenience.