What to do when "peer" feedback fails

I have a situation where a person at my level in a separate part of the company is not delivering the necessary results and it is impacting the company in a negative way.  This person's management is aware of the outages but not knowledgable enough in her work to understand that she is a primary cause of the outage.

I have given some instances of feedback to the individual (did not follow the peer feedback model) and it has not yielded change.  I now need to approach her management to explain the problems and the proposed fixes.  Any advice here?  This needs to be done - I am looking for help on how to do it as professionally as possible.

Thanks.