BRMC
Striker
It's does eventually. I had to fight EDF for mine. Had been asking for for my refund for about 5 months off utility point and then EDF held on to it for about 5 months as well.
Had to threaten then with the ombudsman and I stopped paying. Told them I wasn't paying again until I got my refund. Bill was eye watering when I finally settled it mind. But my credit was 800.
I would chase them
I think I was around £450 in credit.
I can't see anything on the British Gas website showing I have been given the missing funds.