Financial Assessment Energy Costs

Hi all, just wondered if anyone had any knowledge with these financial assessments when it comes to the Energy cost discount.
This assessment for my daughter has been going on, under appeal, since November 2023 where we were told in the first report that the National Average Cost for 2 or more people living in a 3 bed semi detached was £3872. This was the initial figure giving in the costing at the beginning of the assessment before I requested it goes to appeal.
The appeal is still on going but today I have now had an email back saying that a semi detached property with 4 occupants is now the National Average Cost of £4912!!!
We have spoken to the energy supplier and they are sending us a revised predicted bill of over £3900 but I just wondered where you find the information for these National Averages as I have search high and low in the gloom of the tinterweb and cannot find the information
Anyone had any experiences or any knowledge at all please? We know these councils are short but to keep moving the goal posts is infuriating especially as they expect us to pay the back dated money (12 weeks now) and Ive told them that I refuse to pay the whole of the back dated monies as we have played ball giving all the information they need yet they are dragging their heels (or there is sadly not enough staff in the office) The lady I am dealing with asked me to explain a geberit toilet and when she understood replied ‘ I thought you only got those toilets abroad “
Any help you wonderful community?
Many Thanks

This one is for carers helpline or citizen advice.