The firm behind Diamond and elephant.co.uk insurance brands blamed unsuccessful TV ads for a 35 per cent plunge in earnings at Confused.com during the six months to June 30.
Cardiff-based Admiral admitted Confused.com was no longer market leader, slipping to second place this year after a difficult six months.
Competitors have fared better with their campaigns, with moneysupermarket recently thanking its 'haggle hero' series featuring comedian Omid Djalili for a 5 per cent lift in revenues.
But Admiral said it had responded quickly, pulling back on current ads ahead of a new campaign that will roll out in the next six months, as well as cutting costs at the Confused.com operation.
A good performance across the wider Admiral group offset the Confused.com troubles, with interim pre-tax profits up 21 per cent to 126.9m. The leap came after it hiked premium rates by 22 per cent year-on-year.