150mbps 5 times slower than at&t 50mbps plan

I got the 150 mbps plan and have gotten over 50 mbps the whole time I've tried everything disconnected all devices, used a ethernet wire moved the modem/router. Tried several modem/router. I came from at&t with a 50 mbps plan that was so much faster than this plan. I'm sick of of it. Customer service has been no help at all and spends hours accomplishing nothing. As far as I can tell this happens to most people, is there anything that can be done considering they are bullshi*ting everyone about the speeds they'll get.