Gigablast not so fast

I signed up for Gigablast a few weeks ago but I'm only getting about 150, which is what I was getting with the package I had before, but I was paying a lot less.  I've tried 2 different 3.1 modems but it's the same speed.  I even had a tech come out to test it, but he said was was getting a gig to the modem, but when it hit's my computers I'm only getting 150.  I don't know what else to do.