AT and T Advertising Solutions, AT&T Negligent loss of URL and Breach of Contract St. Louis, Missouri

AT and T sales rep offered the use of a catchy URL "owned" by AT and T. The URL was prominently placed in my print advertisement. After book went to print, I was informed that AT and T no longer owned the URL. It had been registered to a private individual in California. AT and T offered to reimburse me if I purchased the URL from the private individual but that happened 5 months after the books came out. Now AT and T wants me to pay 65% of the monthly rate on my ad for the 5 months that the URL was defunct. I lost 5 months of business not to mention the hours I have spent recovering the URL and communicating back and forth with AT and T. AT and T was negligent in their nonprotection of this URL and AT and T has breached our contract.All I want is a writeoff of th bill for the five months that the URL was defunct and credit for the cost of the URL.Where is your fairness AT and T?