SBC / Yahoo DSL 2

i have sbc yahoo dsl for a week now and i want to get rid of it i am supposed to be getting 1.5 mbs but when i download anything i get 54 to 76 kbs and during the instalation of the software when it would get to the end where it was trying to connect to there servers it would stop say there was a problem with the connection so i had to call them to set up my account and now the internet is slower i want to get comcast now or have this fixed i called them and told them thats its downloading slow they told me i sould be downloading at 1 mbs