Verizon billing for service not provided

Verizon sent me a bill after I canceled my service on 11/21/09. The bill is for services from 11/17/09 to 12/16/09. When I called about it, I was told that since I did not cancel my service on the end of the billing cycle, I had to pay the full bill. I was told that I signed a contract to this effect. When I asked for a copy of the signed contract, I was told I could not have it.