Actress Michelle Keegan backed a treatment priced at £2.50 in a national rollout.
She referred to it as a 'godsend for holiday hair' in latest press coverage.
The promotion gives a £10 discount on the product, which has become well-liked among her fans.
Wales Online reported a £12.50 version of the mask renders damaged hair 'liquifying' after a single wash and received rave reviews.
The Liverpool Echo labelled it 'one of the best ever', reflecting Keegan's endorsement.
The Mirror, Wales Online and Liverpool Echo all released stories on the discount.
The discount has boosted strong digital interest.