The complaint made against the ad claimed the broadcaster’s offer was "misleading" as it did not make it clear what else customers needed to purchase to benefit from the £7.50 offer.
The ad, created by WCRS, featured Willis playing himself as he storms into his broadband provider’s office to complain about a pop-up message on his laptop saying he has exceeded the download limit while streaming one of his films.
The ad ends by encouraging users to "demand more from your broadband" and promoting Sky’s Unlimited Broadband service for "just £7.50 a month".
In order to purchase Sky Unlimited Broadband at the advertised price, customers also needed to buy a Sky TV subscription worth between £21.50 and £62 a month, as well as Sky Talk and line rental for £14.50 a month.
However, in its defence against the complaint, Sky said the commitment required to obtain the unlimited broadband at £7.50 was "made clear" through the on-screen text.
The on-screen text at the beginning of the ad stated: "Sky TV from £21.50 a month. Box and set up costs may apply". During the voiceover announcing the offer, the text read, "Price for Sky TV customers. Sky Talk & line rental (£14.50pm) required."
The company maintained that as both the price of the Sky Talk and the Sky TV was given in the ad, the "average customer" would understand what was needed to get the deal being promoted.
However, the ASA found the ad was misleading as it said the costs of the Sky TV and the line rental should have been shown more prominently in the ad, as they were needed to benefit from the advertised offer.
The ASA considered the on-screen text a "small print" and said it was "significantly less prominent than a claim made in a voiceover" and was therefore "not an appropriate method of communication material information relating to the £7.50 price claim".
It also said that the price of the Sky TV needed to be shown at the same time during the voiceover rather than 15 seconds before, at the start of the ad.