They have always done that if you let them. I simply don't let them. Southern have just tried to up one of my DD's from =A315 to =A333, well = they did for a while as I owed 'em a bit but then I phoned 'em up and got it =
reduced. I think they also tried to up the =A32 one but I stopped that increase before it started, still pay by DD though. When ever a bill lands on the mat I check the readings, if I've used less I tell 'em, if =
I've used more I don't.
More fool you for letting it get that big.