MKM's handling of the promotion attracted 19 complaints, compared with the 101 complaints about a cruise promotion, also in the Daily Express, in a case upheld against MKM only a month ago.
An Advertising Standards Authority spokeswoman said that its compliance team would be speaking to MKM.
Two other cases went against the company in January. One involved a flight promotion on cases of Ernest & Julio Gallo wines and the other a similar promotion linked to consumers signing up for BT Broadband. Another investigation involving MKM is ongoing.
The case heard this week concerned a promotion in the Daily Express for travel to the US, which offered either cheap flights or hotel and flight deals, available between October 2004 and March 2005.
MKM admitted that it had experienced administrative problems handling two major promotions simultaneously, and had been overwhelmed by demand.
The ASA ruled that MKM had poorly administered the scheme to the extent that people who had applied for flights were not contacted to be booked on to them before the day allocated to them for travel.
However, the ASA did not uphold complaints that the promotion exaggerated readers' chances of obtaining free flights. It also did not attach any blame to the Daily Express, which this time responded to the investigation.
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