Incorrect Billing on Contract

<p>Hi, I would like to know why I am being billed for the incorrect amount on my package as well as a month prior? I recently upgraded from a smart M to a Samrt Top Up L+ during May. I was advised that the contract would come into effect 1 June, this has not been the case. Today 31 May my contract was upgraded to my new package and now I have been billed R 719.00 for my line rental for the month of May which I should still be billed at the old rate of R 320.00. Further to this te contract that I signed for was and is advertised as R 499.00. Now including VAT that may come to R 568 but not the R 719.00. Please could someone contact me to rectify this as this not correct. </p>