I have never heard of them. Best thing to do is check on the .gov website that they are definitely registered as competent persons.
If they are registered then it should mean that they have been evaluated on a yearly basis, and also many of the schemes such as Napit and NICEIC will actually guarantee the work of their Registered companies.
It is usually better to go by recommendations or word of mouth or off of a recommendation website such as this.
Hope you get it sorted.