Nationwide Insurance I cancelled insurance but still got charged Columbus , Ohio

I decided to cancel my homeowners policy with Nationwide Insurance for a better rate and they would not pay the one small claim I had in 20 years, so I personally went to the agent's office to cancel 4 days before the policy payment was due. The agent told me it was too late to stop payment, as I authorized an automatic withdrawal from my checking account. 4 days early? She told me I would receive a check in 7 to 10 days. After waiting 4 weeks for the check, I went back to find out where my money was and they had no clue, I waited a good hour while the agent made numerous phone calls, and found out that they were taking $15.00 for "prorated time". I then proceeded to tell them what I thought of this rip off and I'll do my best to convince others not to use Nationwide. I also told them that I will come to the office every day until I get my check. Later that day, I received a phone call from the agent telling me that if I come into the office anymore that I would be arrested. It was a couple more weeks that I was reimbursed, minus the $15.00. How can they prorate my refund when I was 4 days early?? How can they withdraw funds earlier than the time agreed? Luckily, I had the money in the bank, or I could have been assessed outrageous bank fees. Nationwide is in your side (and your wallet as deep as they can get).