Running around for two months for an unactivated contract upgrade

At the end of May (two months ago) I received a call from Sell Direct on behalf of Telkom to offer an upgrade of my 20GB data contract to a 40GB data contract. I was happy with the offer and accepted it, receiving the router a few days later. However, two months later I still have not yet started receiving the 40GB per month; instead, I am still only getting 20GB per month. In June, I contacted Sell Direct about getting the upgrade completed, and was told to wait a few days as it should sort itself out. Then I was away from South Africa for about three weeks; upon coming back I contacted Telkom to just cancel the upgrade since it still had not yet been activated, but they told me that only Sell Direct could process a cancellation as the deal had been initiated on their side. I called them, only to be told that their systems were offline and so they could not do a cancellation. Then I was overseas for another week and called Sell Direct today. The consultant tells me that only Telkom can do the cancellation, but when I go to Telkom they tell me again that since Sell Direct started the upgrade only they can finish it. This whole experience has been terrible! Can I just cancel this upgrade? Sell Direct can even have their router back.