A longtime USAA customer, who has filed a lawsuit against the company in San Antonio district court, claimed the insurance giant refused to provide towing assistance after his vehicle broke down nearly two years ago in Matamoros — three miles from the U.S.-Mexico border. The suit, filed in February by retired Air Force major CL Lucas, accuses USAA of deceptive trade practices and breach of contract.Lucas’ suit seeks more than $1 million in damag…