The animated television ad showed a house on a spinning planet before a voice-over reported that the boiler had stopped working.
A British Gas van appeared and a man walked from it into the house, with the voice-over saying: "Sometimes you need a little help there", and adding: "Which is why you can reach us every day. Even over Christmas" and "Look after your world this Christmas with British Gas."
Eleven viewers complained that British Gas misleadingly implied that it would attend call-outs and carry out repairs on the same day, or at least very quickly, particularly over the Christmas period.
British Gas disputed the complaints, saying it was not the company's intention to advertise the speed of their response, but to demonstrate to viewers that British Gas would deal with all queries, even over the festive period.
They believed a high level of service was achieved despite adverse weather during the festive period, which affected their ability to respond to same-day and next-day call-out requests at the level expected.
The Advertising Standards Authority (ASA) upheld the complaints, noting that the ad gave the "overall impression" that customers could expect an engineer to attend on the same day a problem was reported.
It added that: "Because this level of performance could not always be achieved, the ad was likely to mislead."
The ASA ruled that the ad should not appear again in its current form.