Golf lessons in Milwaukee WI?

Can anyone recommend a reputable and experienced worthy golf instructor around the Milwaukee WI area? I'm not a beginner and in fact, I'm a 13 hadicapper seeking to improve my golf game. I've been playing for 3 years and never had a lesson before. I know that there are many out there at the county courses and golf gax but I'm looking for advance knowledgeable instructor. Personal experience will be preferred and appreciated.