Incorrect Charge

Recently upgraded my contract for cell number ***. I was informed by the online team that they would cancel old contract and then move my number over and only bill for that one. I then went in store and they confrimed and updated. This month i was charged R1595 a PRo rata for the R310 new contract for 2 months and then the remained charged for my old contract which I was told was canceled. I want this refunded! This is not the first time Telkom has done this to me.