NTL News wrote:
If I have the heating set so that it comes on at 8am for an hour and brings
the house to 20.5 degrees and then drops down to 17.5 degrees during the day
and then back up to 20.5 degrees from 5pm until 11pm, then 16 degrees
through the night, it is costing me over £100 a month at this time of year.
Sure it heats up the hot water as well, but it is only two of us and the hot
water is only really used for a couple of baths a week as the dishwasher
heats its only water and so does the washing machine.

I had no idea that heating a house would be so expensive even with one of
these so called economical boilers. Is £100+ per month about normal for a
house like mine?

Not really, unless you leave the doors and windows open, or live
where it's extremely cold. The indoor temperatures you mention
aren't excessive, either. Have you got a leak, or a meter prob.?