We bought an expensive 'combi' unit 18 months ago, after spending half an hour in the store explaining what our needs were (this included talking about specific diameters of gorse). We were assured that this unit would solve our problem and a few others. The machine has been in an out of the service department constantly (three times while on warranty) until finally last month we were told the machine isn't meant to do what we are doing with it (which was precisely what we'd explained to the sales person we were going to do with it). When we asked what they intended to do about it: because they'd obviously sold us the wrong unit we were told point blank that the staff NEVER make mistakes that we obviously had explained our needs wrong. It was some of the rudest treatment I have ever experiences from a salesperson: he basically accused us of lying, of being incompetent (my husband has an engineering background) and trying to take advantage of them (though we were asking them to suggest a reasonable solution -- in end they offered us $600 worth of trade in on a system that has cost us $2000)
When my husband related this story to a friend (a builder) the friend said this store has a terrible reputation for this kind of thing and he personally refuses to give them any business. We're now joining him in that opinion.