Failure to cancel account

I sent in my notice to cancel my services on 14-08-2017, my account was suppose to be canceled on 15-09-2017. So far I've been charged for the all month as well as every month so far.

I've called the accounts department multiple times, they promise the account will be canceled and the account will be amended but they have still failed to cancel my account.

My last ref number was ref ********** 03A