Billing issues that are *******

I have been with Rain for about 2years as a customer they keep telling me I am in arrears however according to my bank statement I am up to date I cancelled and my service is to end now they collected my router on the 10th of August and I had no service since cancelling before that and now they trying to take money out of my bank account which is utter nonsense when you call the support they don't answer , this is surely ******* what they doing but I have never received such horrid disgusting service from an ISP.