STOP DEDUCTING FROM MY ACCOUNT

I cancelled my policy with Auto and General months back, but they never cancelled it. They keep on deducting in my account and I keep on reversing. I hate that they do what they like in my account. I have stopped payments many time but they either change reference number or make 2 separate deductions from my account. Im tired of what this company is doing to me. They are messing up my bank account, i always have to pay reversal amounts coz of this company... I BEG of this company to cancel my policy with them because they couldn't help me when i needed them and now they are just plain messing with me.