Nonsense service

Worst ever experience with any network.No joy at all cancelled my contracts in store and my last payment was suppose to go of at end of July and when I called in to verify my cancellation they told me my contract will only end 11 August and i will still have to pay end August and then in the next sentence I was told I will still have to pay end September.why is it so damn difficult just to cancel my contract the first time and why did the cancellation in the store not go through or how can this be explained I already cancelled last month and now I’m being told all this.no assistance from the supervisor at the retentions department