For that last reason I decided I'd fight the decision. I'll cop it on the chin if I've made a stupid mistake, or been careless (not reading a valuation report on one occasion, and on another, using the figure shown on a payslip as Annual Salary and not realising that it represented a full-time equivalent, while my customer only worked part-time) but in this instance I had looked up the relevant product / policy to check before I did what I did.
We have five days in which to respond to any Unsatisfactory; no way was I waiting that long. I thought about it for most of the day, and finally before switching off last night I sent through my response, explaining my actions and requesting the decision be overturned. (also requested that policy be reworded to remove ambiguity, but didn't think I'd get anywhere with that!)
It worked! I've now been "let off" with a stern warning. That made my week, really.