Disputing a bill

Need advice........ How can I resolve a dispute I am having with Direct TV. April of this year I signed up with Century Link for my internet service. During that conversation I was asked if I wanted to bundle with Direct TV . I Did this , with the understanding I had a 13 day grace period to cancel Direct TV with no charge. I ended up canceling before the 13 days were up. Since April I have been receiving emails stating I owe them $253.20 for early cancelation and I will be sent to collections if not paid.  I have spent MULTIPAL HOURS on MULTIPAL DIFFERNT DAYS throughout these MONTHS and get NO where from anyone I have talked to, supervisors included. They keep telling me this is a valid charge. How can this be valid when I was told I had a 13 day period to cancel with no charge. I was advised to fill out a resolve payment issue form from Direct TV, I would be happy to tell them how poor their service is but I refuse to give them my credit card info which by the way is required before one can submit the form. No thank you- just so you can charge it ..... The customer service that I have received from Direct TV...... well let me say this nicely ..... there is NONE.... I will NEVER receive direct TV services again. I also own a rental and when their contracts are up I asked them not to renew.  I will continue to spread the word on their poor customer service.