Energy regulator Ofgem said Britain’s biggest energy supplier had approached it about failure to compensate 12,000 mainly business customers after third party agents missed appointments or did not keep to time.
British Gas has since changed its customer services processes to ensure customers receive their compensation.
It has paid out £30 for an initial failed appointment and £30 for not paying customers within the required 10 days, with an extra £30 on top, amounting to £1.1million.
Martin Crouch, the Ofgem senior partner for improving regulation, said: “British Gas did the right thing in coming forward to report this issue, and has since improved its processes to make sure that, when appointments are missed or not kept on time, all customers receive the compensation they’re entitled to.
“It’s crucial that suppliers keep appointments on time, and make amends when things go wrong.”
A British Gas spokesman said: “We discovered the error last year and reported it to Ofgem.
“We have apologised to the affected customers, given them all compensation and an additional goodwill payment.
“In April this year we introduced new system checks to ensure this can’t happen again.”