Not vital

At the end of July, I called Discovery Health to cancel my Vitality subscription. I was told that since debit orders have already been sent through, my cancellation will take effect at the end of Aug, and the last deduction will be at the end of Jul/beginning of Aug. The person I was talking to even offered me the opportunity of reversing my end of Jul deduction at the bank but I said since I called late, it's ok, I won't reverse it. On the afternoon of 14 of Aug, I received a call from Discovery. The guy was trying to convince me not to cancel. He said that he would email me information that will show me the benefits of staying on. I received the email on the same day but still it didn't make sense for me to continue. I didn't call back since my last instruction was to cancel the subscription. I was surprised at the end of Aug when I saw the deduction for Vitality going through. When I called and asked why did they deduct after I gave instruction in Jul to cancel it. They told me that the guy who called me on the 14th of Jul said that I agreed to continue with Vitality. That was a lie, since never even once did I say that. I said that I'll look at the information that he would send me than decide. Based on that, I then reversed the deduction through my bank, and I thought it was the end of it. I've just received a notification that Vitality has deducted a double amount today and I don't understand why they are still deducting something that I cancelled at the end of Jul. Is that the modus operandi to ***** money from people who don't check their statements? Why did the person who called lie and said that I agreed to continue with Vitality when I didn't say that?