Energy company claims I owe them a bill for a property I no longer live in. (England)

I was living at an address where my mother was paying the bills, we then moved and paid the final bill for that property. We stayed at a hotel for 2 and half years, then moved into a new house and after 7-8 months got a bill with my name on it for £3700 which the energy company says I owe for the previous address. I phoned up and they said I'm still living there, I've told them I haven't been living there. Now I've got a bill of £4000 and they are saying I got 14 days to pay or bailiffs turn up.

Is there any advice I could receive.

Thank you