Neil, thanks that's much clearer.
The UK CAA have an advice line which you can ring and a complaints procedure to follow if you don't get anywhere directly.
I still think the delay was acceptable given the problem and if these airlines had contingency in place for every possible situation then the price of the low cost tickets would rise far enough to put them out of business. That said, what they are saving in contingency is massive compared to paying out to you when things do go wrong!
Good luck, let us know how you get on with the CAA. Even if they can't help with this airline they should be able to pass you on to the relevant body that can.
Referring Your Complaint to the CAA | Resolving Travel Problems | Passengers