The contract between Carolinas Healthcare System and UnitedHealthcare expired Saturday night, leaving thousands of Charlotte-area residents uncertain about where to get medical care and how their bills will be paid. UnitedHealthcare issued a statement that, effective Sunday, all Carolinas HealthCare facilities and physicians are "now out of network" for United Healthcare customers, including employees at Duke Energy, one of the Charlotte area's largest employers. "We understand and appreciate how disruptive it can be when a hospital or doctor stops participating in our network," said UnitedHealthCare spokeswoman Tracey Lempner.