Clear Internet Charging me even though they aren't able to provide me with the services they provide Internet, Internet

I had internet service and moved to a new state. I was told I still lived in a service area. When I moved I wasn't able to get a signal. I spoke with Tech support and they tried everything. They said there was nothing else they could do to get me a signal to use the internet. I called ane cancelled my service on 04/30/12. When I got home I received a email saying my services would be cancelled on 05/20/12. I called back to have them cancel my services immediately. I finally got them to cancel my services, but they said I would still be charged until 05/20/12, which I had already paid. SO I wouldn't be getting a refund for the days I paid for. I argued with them but they said there was nothing else they can do. I understand if they charge people until the end of the billing cycle even if they cancel. But I was cancelling because I'm not able to get the services they provide. So they basically want me to pay for days that I'm not getting any service. I was hasseled everytime I talked to someone to stay with the company. They didn't seem to understand that I wasn't getting a signal and I'm not going to stay with a company if you can't provide me with the services I'm paying for.