Complaint about eon

SodaFarls

Please help with urgent advice. I want to leave EON, I went through the six week period to switch my gas and electricity.
I received confirmation on email that my gas supply had gone to First Utility. I phoned EON to check and they said they not received notification for my gas, just my electricity.
I emailed First Utility and they said it takes 28 days for EON to update their records. I waited 28 days and EON still say they are supplying my gas. They will not taken cancellation from me.

Over the past few years they have increased my direct debit (because they said they had to), from £38 a month to £110. When I contacted the energy switch people, they talked me through my bill and identified that I was £500 in credit with EON.
EON wanted to keep hold of this surplus until after I switched.

I don't want First Utility to have to make a brand new request for my gas, which would mean another six week delay.

Has anyone any suggestions, I feel helpless

Thanks