Lucyella, you may have to resort to the technique adopted when dealing with children. The first stage is to only give 2 options, for example "would you like steak and chips, or cold dog vomit and mash?" (ok, I admit that might be a tad extreme, but just trying sensible options might make a bit of a start.) Another example, "Would you prefer to go for a walk, or dangle your testicles in the food processor?" Again, I will admit that these are somewhat extreme options, but you probably get the drift.
If giving options doesn't work, then you move on to the "Instructions" or "Orders" phase.
The way you manage this is entirely up to you. Still bearing in mind the "dealing with a child" strategy, you may want to try the "Right , we are going out, if you haven't put your shoes on in five minutes, I'll take you as you are" approach or perhaps favour the "Darling, I do think that we really ought to be on time for the play, as that nice Timothy West would probably like to start and finish on time so he can get home before Prunella Scales locks him out."
I'm just waiting for a womans magazine to offer me a position as an agony aunt.
I fear I might have to wait some time............