My account debited for a cancelled policy

I requested a quote for car insurance mid January from Auto&General and took the policy which was to start 1st of Feb as discussed with the agent. The agent captured my email address incorrectly and I never received policy documents. The next thing they debited my account with a pro-rated premium on the 22nd January when I still had my other insurance cover. I was upset by this and had the payment reversed by my bank. I called Auto & General and asked them to send me the policy documents. On receipt of the policy I called them again and told them there was an error in the policy document. At that point I told them I wanted to cancel. They transferred my call to the manager who begged me not to cancel and even offered me a lower premium - which I refused because of the experience I had with them. On the 1st of February they debited my account again with a full premium for a policy I had already cancelled. I called and wrote to them stating I had cancelled this policy. They asked me to send 3 months bank statements which I have sent twice since then and they are still refusing to pay my premium back. Can someone help me with this? It’s been 3months already dealing with the same matter and there is no action being taken.