The Advertising Standards Authority (ASA) has launched an investigation into an ad by bookmaker Paddy Power guaranteeing to refund losing bets if South African athlete Oscar Pistorius is acquitted of murder.
46 complaints were made to the ASA about the promotion, which appeared in newspapers and on social media.
A petition on Change.org has also been signed by more than 115,000 people.
A spokesperson for Paddy Power said: "Despite the ASA announcing their investigation, we stand by our decision to run this betting market and publicise it to punters."
More top news
The Late Late Show host also allowed the singer to take the wheel in a Carpool Karaoke first.
The lender, which is the worst affected by the PPI mis-selling scandal, said it has also set aside £150m for other conduct issues.
Vodafone has been fined £4.6 million by the industry regulator for "serious and sustained" breaches of consumer protection rules.