People with hearing loss are not being offered an adequate level of service from shops selling assessments and hearing aids, an undercover investigation has found.

The RNID, the UK’s largest hearing loss charity, linked up with consumer watchdog “Which?” to send undercover researchers to 28 branches of the five biggest high street companies and independent dispensers.

It described the experiences of the undercover shoppers as “shocking” and it is calling for a review of regulations covering private hearing aid sellers.

More than four in 10 hearing assessment experiences were rated “poor” by audiology and trading standards experts, the study revealed.

Researchers posing as customers visited Specsavers, the Hearing Company, Hidden Hearing, Amplifon, Boots in-store David Ormerod centres, regional chains and independent dispensers to test clinical assessments, communication, product recommendation and selling.

They found that not one company was good enough to recommend, almost half of hearing tests were not carried out in a soundproof booth, and half the dispensers failed to ask basic health questions to determine whether the hearing loss was caused by a treatable medical problem.

RNID chief executive Jackie Ballard said: “We are very concerned that people with hearing loss are not always receiving the level of service they’d expect.”