CHARGED FOR A PHONE RETURNED TO VODACOM

I have been dealing with Vodafone Customer Care, accounts and retentions for almost 2 months for a botched cellphone upgrade and cancellation. They have charged me an installment at the end of March for a phone that was returned to them at the middle of March. They have also added a balance of equipment charge to my April invoice to the amount of R13000+ for the same phone that has been returned. I have logged approximately 6 calls with them to have the upgrade cancelled and charges reversed. All calls have been closed with no resolution and upgrade and charges still reflect. I am now told after the last call was closed that the credits have been approved but will take up to 21 days to be processed. In the meantime the exorbitant amount shows as it will be debited on the 30th of April 2018. I started the process of querying the April invoice on the 2nd of April to give them a time to resolve it since half a month was not enough in March, but I still in no better position. Each time the calls are assigned to people who cannot resolve them, they close them without any feedback to Me. All of this inconvenience and frustration is because a call center agent agreed an upgrade package with me on the phone, but processed something else.