If someone says to you:-
"Employers are crying out for people with this qualification, and look, we've said as much in our leaflet" You would be on stronger ground. On the one hand we need to consider whether that comment is true - are employers really crying out for such qualifications? - and on the other hand we have your word for it (which I have no reason to doubt) that this representative really did say that.
If you can demonstrate that:-
1. Employers are not crying out.
2. That you relied on the representative's comment when making the purchase.
You have a valid case for a misrepresentation action - the representative could be said to have misrepresented the value of the qualifications in an attempt to induce you to purchase. It's illegal to do that, and you would have the proverbial open and shut case.
The problem, of course, is in proving that employers don't cry out for these qualifications - it's one thing for me to say that they don't, and for others to share that view, but we're merely expressing opinions. You need facts, and the only way you'll get those is to contact some employers and ask the obvious question - are they crying out for people with those qualifications. Get a few of them to say they're not, and you have a case.
Scheidegger allude to IT jobs on their website - "If you would like to know how to become a computer network specialist and to earn £25k(+) per year, fill in the contact form to discover more about the job opportunities and career options." but as far as I can see they make no unsubstantiated claims - they simply refer to the N+ as being "the industry's examination of choice for computer network engineers". Undoubtedly there will be IT directors who say that's correct, and there'll be those who say it isn't - and that's the problem.
My own view is that qualifications are useful, but they are not in themselves the golden key to well-paid jobs that some training companies imply.