Poor service VODACOM

I am very disappointed with Vodacom, there was a special on a data contract. You buy 10 GIG day and for night and you get 10 GIG free. I signed the contract and every month they make sure that they deduct their money , but they don’t deliver. Every month I have to call them and complain that I didn’t get my extra 10 GIG that they have promised. This month they still haven’t given me my 10 GIG and now they told me that I must reapply and submit all the paper work again. This is very disappointing and it’s been only 3 months on this contract and I have been a loyal costumer for me for more than 5 years and this is how they thank their clients.