Vodacom - upgrade app**** to incorrect account.

I went online to upgrade my table device (new device + data contract). Instead of upgrading the contract for the number for my tablet, they incorrectly upgraded my cell phone number contract. To reverse this they say that they will cancel the contract, collect the new device that was issued to me and issue me with a new device when a new contract is established. My question is, what can Vodacom do so that I am not inconvenienced as a customer due to their mistake. I've been trying to speak to an agent that can help but after getting cut off and numerous other calls, I still don't know how to resolve my problem