By her reckoning, it sent her 500 letters in a span of five days.
"I thought I was being punked, that someone was messing with me," Windham resident Stephanie Lay told WCSH-TV.
The letters from UnitedHealthcare were sent to Lay's 19-year-old son, Bryce, who has autism. They were addressed to Maine's Department of Health and Human Services -- in Cincinnati.
"Where is the ME DHHS office in Cincinnati, Ohio?" she is asking.
Most of the letters said the company had denied a $54 payment. Others said payments were being denied for $0, Lay said, for claims that had never been made.
One small irony, Lay said, was that each letter advertised a "Go Paperless" initiative.
A spokeswoman for UnitedHealthcare said the company is looking into the issue.