Upgraded to Internet 50 now my speed are slower than when I had 45Mbps.

Today I upgraded to Internet 50 because it was available in my area. They told me to give it about an hour and then unplug the gateway and plug it back up. I did that and then my speeds went down. I have had technicians in the past visit for other problems and they have told me that I am really close to the box and should have great speeds. To be honest I was always at 46-47Mpbs when I had the 45Mbps plan. I called in and the guy that helped me said it would take about 2-3 days for my modem to register in the system or get an authenticated connection as he said. This does not sound right to me. He also told me with the Internet 50 as long as you are getting 25-50 Mbps you are considered to be good. I asked if you go to a restaurant and you order a plate of whatever and they bring you half the food would you be good? We both laughed but the problem as not been fixed. I just don't understand why it would take 2-3 days for the modem to "register" in the system for me to get the better speeds. Has anyone heard of this before? Is there anything I can do on my end? I am currently getting from 30-40Mbps per speedtest. I have disconnected and reset the gateway many times and nothing.

Rob