The drinks maker reports volume sales dipped by 1% in the two months to 30 April, while revenue slid 3%.
However, the rate of decline slowed from the 4.9% decline in the year to 28 February.
The company launched the “Method in the Magners” campaign in March, the first created by The Red Brick Road. The advertisements position the brand as a quirky drink with a rich heritage.
C&C Group will be hoping the campaign reverses the slump in sales suffered in recent years following the early success of the brand and increased competition from brands including Kopparberg. Volumes declined 17% in the year to 28 February 2009.
Separately, the group, which also owns the Bulmers brand in Ireland, saw underlying revenue, which excludes the impact of acquisitions, decline by 8.6% to €446.4m (£380.7m) in the year to 28 February.
Including the proceeds from these acquisitions, group revenue increased by 16.4% to €568.8m (£485.2m).