Why so strange??…as he is a Spanish lawyer and he is successfully obtaining the numbers for clients I think i will take it that he knows what he is talking about.
I know that you can apply for and NIE at a consulate but as there is only London, Manchester and Edinburgh its hardly one in every major city. The consulates only act as a postbox to Madrid and dont give the numbers. The numbers can take months to come through using this route. i have some clients that appled On feb 5 in London and its still not done so they have missed their completion date of 18 april.
I did say the service was available to anyone who didnt want to travel or the cost would be prohibtiive. The fact that he charges £100 doesnt make him unprofesional. Considering the cost of a flight, hotel, car hire etc to make a special trip for an NIE, I would say its a bit of a bargain!!