Unable to deliver on upgrade deal

Once upgraded on line for a deal, they simply advise that product is discontinued and will not be delivered. Very bad for a company of that magnitude. This in not the first time it has happened, but my second experience trying to upgrade since 13 July 2015. First deal returned and reversed due to similar complaint. This time I took a screen print of the deal as with the first deal they were saying that was never advertised. What will the excuse be next? Please can Vodacom just deliver on promises or is this too much asked from us, the customer.