That's possibly the worst bit of advice I've seen for quite a while.
Even if you look at my original post as being a bit defeatist (which, I admit, on reflection it was and the consensus of arguing your point in court over the £100 is probably a good idea), just ignoring it isn't an option any more. You either need to pay or contest, ignoring it is going to look terrible on you when they take you to court, which they're far more likely to do now they have a much better chance of getting you to cough up.