If like me, you've spent literally hours waiting for someone to answer the customer service number listed (0845 052 0000) try using the following number 0845 300 6301. I had an immediate response.
This is the complaints line number for Eon where the staff are authorised to return credits (£150) in my case and further a contribution £5 towards the cost of my phone calls.
I also insisted Eon stop their intended 20% uplift in my DD charge to me and leave payments as previously agreed. I offered to review again in 6 months which Eon agreed to so result!-Hope this helps.