Any recommendation for a good travel agent in the UK (preferably London) capable of issuing a CMB-originating complex itinerary (12 segments on 5 different airlines)?

I had a rather surreal experience at Trailfinders in Covent Garden last week. I went there with my full detailed itinerary, an ITA print-out and a full summary of flight numbers and dates, booking classes and fares bases and asked them whether they could confirm the price and issue the ticket.
She started by saying that they would not have "special" fares for tickets originating outside the UK, and that they would have to charge a fee. That was what I expected and was happy with that in principle. I asked her what fee they would charge. She said. Oh, it depends on the airlines, the cost of the ticket, the number of flights, etc... I was rather astounded by the answer and asked her whether they charged a fee for each segment. She said yes. Now, I should have known at that stage that she did not know what she was talking about. But she offered to calculate the ticket price and fee, so I let her get on with it.
After a couple of minutes of her typing on the computer and writing figures down, I realised that what she was doing what calculating the price of each segment on a point-to-point basis and adding them up! I asked her whether it was what she was doing and she confirmed it. And this, even though I had actually given her details of the fare components.
That's when I realised that I was completely wasting my time.

She was so sweet and well-meaning albeit utterly incompetent (bless her little cotton socks) that I did not have the heart to tell her that constructing an air fare was not like putting cans of baked beans through the till at Tesco.
OK, I have experienced so-called 'travel professionals' in high street travel agencies a la Lunn Poly which are utterly clueless. Perhaps, I am naive but I expected Traifinders to be somewhat better. Fair enough that not every agent might be expert and capable of dealing with a very complex itinerary. But not having any basic notion of airline pricing and ticketing and not knowing the limits of your competence in what is meant to be a specialised travel agent is taking the p**s.