Heartland Inc. Magazine Subscription Charged my credit card without my permission, and after I sent in my cancellation I signed. They even call at 9:30 pm des moines, Iowa

This company has charged my credit card after I told them not to do so. I was sent a cancellation form if I did not want this. I filled in the information and signed it with a date sent it to the company and they still did this to me. Then they continued with there phone calls. I was informed they had overbilled me. I told them I was not to be billed in the first place. the lady said that I didn't send the paper in time. Which was a lie. I sent it back next day as soon as the post office opened and had it postmarked for that day on purpose. Some phone calls they have made to me have even been recieved after 9pm which I believe to be also illegal.