Based on this, I conclude that Hidden Hearing is an
avaricious unprincipled company that uses a veneer of
medical authority to prey on the elderly and the vulnerable.
I wrote them a letter of complaint but got no response.
Steer well clear of them.
You are of course entitled to come to your own conclusions, but your description of Hidden Hearing is a rather sweeping and generalised. Your arguments about price are not necessarily as clear cut as you are suggesting, as there is a huge range of hearing aids and you would need to be comparing like with like to make a comparison.
It seems to be rather hit and miss when it comes to diagnosis and reading test results regardless of who you go to. In the series of people I dealt with, one hospital consultant told me I had no significant hearing loss, another told me I had, but did a very poor test during which he was on his mobile phone most of the time. Two audiologists told me I had definite hearing loss but gave me completely different information about hearing aids. I knew I had hearing loss as (1) I could not hear and (2) one ear felt (and still feels) 'dead'.
Possibly because it is not 'life and death' (though the hospital consultants charge life and death prices) the whole business of hearing seems not to be regulated as well as it might be. If you buy a pair of glasses you know within a couple of days whether the prescription and product is right. Hearing is much more subtle - and expensive. This seems to be the case right across the industry though. I was fortunate to find a good audiologist and get satisfactory treatment. I also know of people who have been satisfied with Hidden Hearing.