
Sky's offer was £50 of M&S vouchers for anyone who registered online and paid out when the customer nominated a friend for a Sky TV subscription, which was then fulfilled.
Payment was promised within 30 days of the new customer subscribing but the online ad campaign received 55 complaints after customers didn't receive the vouchers on time or, in some cases, at all.
While Sky pinned much of the blame on customers through incorrect registration and ineligibility for the offer (as well as 'citing faliure within the data transfer system'), the ASA ruled that the sales promotion be banned in its current form due to 'unsatisfactory administration'.
The watchdog said that Sky's poor administration had resulted in 'unnecessary disappointment' for consumers and said that the ads can not appear in their current form unless it can demonstrate that the offer will be fulfilled within 30 days.
As one of the UK's biggest brands, Sky shelled out £6.8 million on digital advertising in 2008, according to Nielsen. The £50 voucher campaign is just one of many online ad campaigns run by the broadcaster.