Halfords has misled customers in a national press advert for TomTom satellite navigation systems, which stated “20% off all TomTom Go”.

The Advertising Standards Authority (ASA) decided the advert for three models of TomTom was deceptive because the claim “20% off all TomTom Go” did not relate to a discount on the most recent selling price.

ASA said the advert did not make clear to consumers that the markdown related to the original selling price only.

Halfords said the headline would have been more accurate if it had stated “at least 20% off”, because all three products shown had been discounted by at least 20%.

It added it had therefore undersold the offer but was still in compliance with advertising regulations.