I'm three miles away and I easily get 3 Mbps. Check your line (mostly attenuation and SNR). I've got 53dB attenuation and a SNR (ratio) of 10dB. Plus, uptime is pretty good (over 13 days now).
They claim to know that it is not the phone line itself. What are you using to measure the attenuation/signal to noise? I have to say the upload speed being faster than the download speed, together with the lack of any drop-outs or instability in the connection did make me wonder about rate limiting.
