Worse service ever, ****mers. Contract ****mers

My contract ended on the 11th of August, i was told that I will make my last payment on the 1st of September and I was debited that amount, I was offered an upgrade which I declined and told the representative over the phone that I won’t continue with the contract, I’m receiving an email again this month claiming that I will be debited another amount because I did not close my contract, which does not make sense because why did I then get an email stating that my contract has ended…. Why am I being ****med? My contract ended in august but I’m being made to pay for 2 extra months