I have usd the same agent for the last 15 years for all our complex travel arrangements, and never been unhappy. When something did go wrong (once, as it does) she sorted it all out and I didn't have to do a thing.
I wouldn't use them for simple things, but when it comes to exotic type holidays with lots of travel or remote locations, we rely on their knowledge and I am happy to pay. having a UK address still, also allows us to take advantage of holiday protection rules rather than booking it locally with less than safe companies locally.
With the £ up the spout at the moment however, we aren't using them as the exchange rate messes up any value they may add, as I don't live in £ land.