Yes you would need to contact them but you said you already are?
I'll have to give Eon some credit; I emailed them about adjusting my direct debit to what I think is reasonable consumption (different from theirs) and they have responded and altered my DD as per my request. Well done Eon.
Here's my reasoning, working backwards from the DD amount:
DD Amount | kWh Unit Rate | SC p/day | SC p/m | Days | kWh p/m in £ | kWh p/m | kWh p/day |
£ 145.00 | £ 0.2791 | £ 0.6375 | £ 19.13 | 30 | £ 125.88 | 451.00 | 15.03 |
I'm sure 15kWh per day is plenty even in the depths of winter as my heating source is oil.