<prompt> Translate the following text to EnglishIRS inakabiliwa na changamoto wakati inarekebisha Ofisi ya Mtetezi wa Mlipaji wa Kodi GAO-GGD-9124, Julai 15, 1999  <response>: IRS IRS Faces Challenges as it Restructures the Office of the Taxpayer Advocate GAOGGD-99-124, July 15, 1999. 