Unauthorised Upgrade

I have multiple contracts with Vodacom and have had for years. I contacted their cancellations department to cancel a contract that had come to an end. The operator of course offered me 'cheaper' installments on one or two of my existing contracts - when he made the offer on one of my contracts ending in June I declined the offer saying that we intend to cancel that contract in June when it ends. I was then unpleasantly surprised to find that the contract has been 'upgraded' by said operator and now only ends in 2021. I did not authorize this upgrade, did not receive a new mobile device and the package is the same and yet Vodacom thinks I am now going to pay for another two years for this! I was told the operator would contact me and of course, no phone call to date. Then I was told that I must lodge a dispute and write a long explanation of what took place with a copy of my id and specimen signatures and now I wait. I think it is terrible that the client has to run around for a mess that the Vodacom staff make and I most probably will lose another month's premium. This is poor service - especially for a long standing customer such as myself.