LANSING — The agency overseeing Michigan’s utilities said it’s investigating estimated billing practices by Consumers Energy Co., which have prompted customer complaints. The Michigan Public Service Commission said the investigation announced Tuesday calls on the Jackson-based “utility to provide detailed explanations about its estimated billing practices.” The commission said “problems have persisted for several years despite repeated meetings” with Consumers Energy. Consumers Energy spokesman Dan Bishop said the utility is working with the commission. He added bad weather and dangerous animals have prevented some workers from doing actual meter reads, but the utility is “making progress” on reducing estimated reads. He said Consumers also is accelerating installation of upgraded, smart meters. The utility must file a report by Feb. 18. The commission plans to produce its analysis and recommendations by May 18.