British Gas

If you've moved supplier or switched energy companies, you may have left credit behind. Energy companies keep records of their past customers, but to help speed up the claim process, you’ll need to have proof of:

Your identity (such as a driving licence or passport)
Address that you’re claiming for including the postcode if possible (an old bill)

To find out more about British Gas’s claim process, you can:
  Call:
Landlines: 0800 294 6654

Write:
British Gas
PO Box 227
Rotheram
S98 1PD

Or visit:
www.britishgas.co.uk/are-you-owed-money.html