After signing the contract they just say sorry no stock

I am very disappointing in Vodacom. Not a specific person or shop but rather Vodacom who creates deals, advertise it and after the contract is signed they say sorry no stock. Knowing very well there was only two available for the entire shop. Then they aren't willing to do anything about it. They just say sorry we are reversing the contract. How is that for client service. Not the first time either! Do not understand why they treat their clients so horrible and expect us to pay more for their services then the other providers.