Without try to flame the situation (honest!) why not pay the bill when it arrives and not pay on the reminder then you don't get cut off?
I'm not quite sure if eyeyex is saying that he doesn't get his first bill or not but he seems to be waiting for reminders which is probably not the best course of action and puts him more at risk of missing the cut off date and then getting restricted!!!!
Reading it again I think it's the first bills which are turning up late, is eyeyex getting problems with other royal mail letters or is it the infamous ntl bill generating system again?