No cancellation has been done!

With a lot of frustration and phone calls and even went into the Vodacom branch they could not assist in sort out my problem with a laptop they have send me and I send it back due to the fact that what they told me, and the package I received was not the same thing.. They send me reference numbers to say that the contract was cancelled but still bill me for the second month +-R700 where my account should be R350..ref. no. 1- ********** ********** on the 24/11/18 and ref. No. 1- ********** ********** 3on the 21/12/18 and I went into the Vodacom branch this week and still this issues is not been sorted and I get charge for something I don't have not use and I am not very happy due to the fact that even though I phoned and was promised it will be cancelled which did not happend and went into the branch and they could not assist.. What happend to competent staff to assist our customers with issues and in the mean while I am carrying the bank cost of Vodacom faulty deductions.. Who can assist me in this matter to resolve my problem?