There are better modems than the 5200. The current one they give out is the Actiontec. One benefit of this modem is it can take care of the PPPOE connection for you instead of your router/PC. You can also log into it and it will show you your connection profile speed.
I had my profile speed drop and I was getting a slower upstream similar to what you are seeing. A tech replaced a connection outside of the house, made a call and got my profile changed restoring my speed.