Hello JP. I looked at the freeserve offer and noted in the small print that only 2000 people would be allowed online at any time!!.
So I suspect you are right that they are fobbing you off due to the fact that 1999 people have since turned up online without problems.
I recently signed on with BT internet pay as you go, due to daytime rate being 2p a minute. (Half that of Gateway with it being my favourite number). Sadly this has flow rates as low as 14000 kbps during the day meaning that whilst you pay half price you take twice as long.