DSL Extreme Claim That I Have Violated a Contract northridge, California

Had internet service disrupted for 8 days. Called DSL Extreme to cancel service due to poor performance. Customer service told me that I was due a refund. Never received refund and then was billed for $231.00 for early cancellation. DSL Extreme claims that I violated a contract. I never signed a contract. I have requested a copy of the so-called contract with my signature. After 3vrequests I have never received a copy of the "phantom" contract. To date a collection agency has contacted me for payment. I asked them for a copy of the contract. So far no response. I cancelled my service because after 8 days DSL Extreme's tech support could not fix my connection issues.