Don't order online @Vodacom ever!

I have tried to order online twice now and both times vodacom had canceled my order without my concent or knowledge and nobody at their call centers or stored is able to tell me why, this is after I have processed the order, instead of keeping it there until they are able they cancel it. The frustrating part is that they did not notify me about this and just did it, here I am waiting for my order only to find out it has been canceled, this is illigal isn't it? As it is without my knowledge or concent