This piece had such a good response it paid for itself within the first 5 days of being mailed out. In one month, Carphone Warehouse received £3.50 in gross margin for every £1 spent on the campaign. This mailer has delivered a massive 233% increase in sales compared to the previous best performing activity. With an overall response rate of 3.6%, this continues to be The Carphone Warehouse’s most successful monthly upgrade activity.