Not keeping to promises

I upgraded my contract with vodacom online via telephone. I upgraded to the new samsung s6 edge which comes with a wireless charger, samsung cover and a voucher of some sorts. So when I received my package I realised there was no cover. I phoned vodacom and told them I did not receive the cover. When I ordered the phone there was no indication that the cover was out of stock and they also asked me what colour I wanted. They first asked me to package everything and the courier will come fetch it in 14 days and only thereafter i will receive my phone and everything back which I was not happy with. After 2 days of fighting with them they finally said they will send me a cover and I will receive it in 5 days. Today I phoned again after not receiving the cover and they said that they do not have stock and because it was a promotional thing I will not be receiving the cover at all. I think it is terrible customer service as that they are lying to get contracts. I am totally disgusted that they are not willing to send me a cover they promised twice. I am furious with their attitude and the lady I spoke to was very rude and did not come up with any solutions.