Can't upgrade

I was told make your payments on time for 6 most then you can upgrade your phone and not to mention I pay for the service to upgrade 2 times a year I have made my payments on time even early for more than 6 months they still won't let me upgrade I need a new phone and have for quite a while !  But nope they lied now I'm looking to get phone service elsewhere I'm sick of being lied to by comcast