On the back of this I do not know any qualified EP's who need to advertise and certainly none that would be as cheap as £20 per trim. In this case you are certainly getting what you pay for and give it a few trims and you will see the detrimental affect he is having on your horse.
We have paid a lot of money and spent a long time getting our qualifications, and so with our knowledge and experience we are treating the whole animal, not just 'doing a trim', so we charge accordingly.
This is the sad state of the industry though. There have been attempts to regulate all of those who trim hooves, something that all EP's fully support, but sadly it hasn't happened yet. So anyone can set themselves up as a hoof trimmer with very little knowledge, as appears the case here.
Nobody should take for granted that the person they employ is knowledgeable, experienced and can actually do the job they advertise they can. We all know about cowboy builders and plumbers, mechanics, etc., but there are cowboys everywhere. It is up to you, as the responsible house, car or equine owner to ensure that you get the proper qualified, safe service you are paying for.
The onus is on you for your equines care. It does not matter if it is the vet, chiropractor, riding instructor, farrier, trimmer or any other professional person you pay to attend to your animal, if you are not happy, get a second opinion, question what they are saying or doing, do some research of your own, do not put up with it,, are they qualified and can they prove it. If it was your house or car you certainly wouldn't, and quite often your horse is the third most expensive thing you have bought. Think about it.
If you own an animal you have to have some sort of knowledge as to how they work. Luckily for us horses are built in a similar way to us so even a lay person has some sort of clue as to what is right and what is wrong.
I have always advocated that owners need to educate themselves. You do
not need a Degree in the Equine Sciences, just a good bit of common sense, get to really 'know' your animal, their moods, their idiosyncrasies, their normal gait, etc. Then you can soon pick up that 'something isn't right' at the moment or indeed after any procedure has been done on them.
No horse should be at all lame or sore after being trimmed or shod, so if your horse shows that there is something wrong you must act. Straight after a trim you should be able to do your normal riding.
It can be difficult finding the right qualified person for your horse, but they are out there somewhere. Do not let that put you off getting rid of the one who is gradually crippling your horse and looking for the one who can give you many more years with a healthy happy horse and owner.
It is your money and your animal, spend wisely for many happy equine years together.