Takealot does not honour advertised prices.

I ordered 2 packs of the Giotto children's modelling clay 12 x350g, which was advertised at R66 (77% discount). Furthermore to qualify for free shipping a minimum order of R450 is required and I ordered further items such as diapers and crayons which I did not need and which were cheaper elsewhere. I paid for these items and received a receipt. However when the items arrived, I did not receive the 2 packs of Giotto modelling clay 12 x 350g . Instead I received 2 packs of Giotto modelling clay 10 x50g. I immediately asked for the correct items to be shipped. I was then informed that the item was incorrectly listed. I asked that Takealot/the vendor honour the sale, however they have refused to do so. At no point was I informed that the item was incorrectly listed, before my order had been processed. Otherwise I would have cancelled the enter order. I have returned the incorrect items and have now received an email from Takealot to say that the item I wanted is not available and I have received a credit. The item I originally wanted is still listed on their website, but now at a higher price. If Takealot cannot honour the price of a small, cheap item, which it has advertised, how can one trust the website and purchase more expensive items, such a electronics etc.