It seems that BT are quite prepared to take extra instructions from our customers on some occasions, and this has caused some dispute. As a result we have added the following to the terms. We think it was pretty well implied before, but this makes it clear and we always like to be clear.
It should not really need saying as it would most probably apply under tort law anyway, but if you deliberately do something knowing it will cost us money, over an above the normal costs for providing the goods or services we supply you, then you have to compensate us for that extra cost. For example, if you ask the BT engineering installing your line to do some extra work and we get billed by BT for that.