Initial phone interview, then brought on-site to go through the rest of the face to face interview process with the manager and another QA Engineer

I have applied online for QA Engineer Profile for Web based Platform. The whole process took 4+ weeks .Since I was a fit for two job roles one related to web and other for mobile platform. They called me asked to give interview for both the profiles. After giving total 6 rounds of interview (4 technical + one with VP + senior HR).They told me will be proceeding ahead with my candidature and offer letter will be given in a week. When I didn't got any update from them even after 1 week ,i called them .So they conveyed that the profile for mobile platform is already occupied. So I told them that I have been interviewed for both the profile ,so they informed me stating that since your interest is more towards mobile platform we will update you after a month if we have any vacancy. It was a complete waste of time and still this company posting job for the same profile.