British Gas - Received a bill thats not mine

monkeynuts2020

I dont know if anyone else can help with this, I use to rent a property until November 2018, and i was with British gas, i gave my final meter reads and paid the final amount when
I moved out of the property in November 2018.  After i moved and resided in Spain while working in Gibraltar, In March 2020 due to the COVID-19 Situation i lost my job and my apartment so i had to move back to the UK, At this time i was staying with a friend temporarily until i moved into my own place.  After 3 months living back in the UK, i receive a letter from a debt collection agency stating that i owe british gas £809.28 between the dates in which i was not even living in the country. i Have phoned British Gas on numerous occasions who said this is being looked into, and i am still awaiting for an answer after exactly a month later. Tonight i have sent an official complaint to British gas as i am now experiencing Anxiety attacks every time i hear the post being delivered, or someone knocking at my door.
I hope someone can help me with where i stand with this.

monkeynuts2020

Sorry i forgot to add in the above thread is that my old account was closed when i moved out. And a new account was opened in my name

dogshome

By sending a written letter of Compliant to BG you have done exactly the right thing, and whilst it is under investigation the Debt letters should cease