It's so hard to know what to do isn't it. I actually ended up doing the Society of Master Saddlers foundation course in saddle fitting because I got sick and tired of being unhappy with the fit of my saddle but not feeling confident enough to disagree with the saddler.
All I can say is this, if you chose a person who has the master saddle fitter qualification you will have some form of comeback. If they aren't a member of the SMS you have to take your chances if you have an issue.
Here is the link to the Master Saddlers site http://www.mastersaddlers.co.uk/
it's worth spending a few moments reading the section on saddle fitting and finding a fitter.
I think that when you phone a fitter one of the first things you should ask is their qualifications. I'm sure in other areas of the country there are people who are really good but not qualified - my experience of fitters in the South East has not reflected that.