after downloading shows "erro"

Does anyone know why I can’t finish my installation of the Avast 4 Pro. It syas it has encountered an error and can’t finish. But nthing else.
Also, I chose the 2 year with a bonus of the 3rd yesr free, but it charged me for 3 years. I wonder what is the matter with this site.
Thanks for you help

Hi Eva,

Are you sure download it completely for avast software?