consistant billing error due to bad sales

I refers to my case no. ***9 loved on march 07 2016. Again I had an unauthorised data bundle billing on my account, after countless an painful calls every single month the issue still persists, shockingly your sales team has never even bothered to contact and apologise about constant errors. Please have this issue corrected before my billing gets debited from my account. It has been over two weeks and nothing has been done. I will take this matter to the telecommunications on buds man as I cannot deal with bad service any longer. The specific number in question was due for an upgrade but we decided not to upgrade but your sales team failed to notify us if we don't select a new package we need to fill in a form to move to pay as you go. Very bad sales. Wewil be cancelling this contract and I better not receive another billing with incorrect or unauthorised amounts on my account.