For those who are interested I've stuck a page on the Griffin Site in which I've tried to be clinical about the issues and put some illustrations based upon data sent to me by a couple of AOC holders over the weekend.
It can be seen
here
I thought it best to seperate it from this thread to keep the issues away from the opinions.
The AOC Charges tool does seem to work and has got all the ones correct we've tested it on up to now. I have however modified it this morning having been fed the scale of target charge percentage increases in the next few years ,this morning.
GS