If they're in a conservatory I would just leave them and enjoy a bit of colour in mid winter. If you cut them back and they're in a conservatory they may start to regrow and become lanky, and the soft new growth may not be as strong as it should.
You can cut them back in the spring when they'll regrow properly.

I would take off any dead leaves and flowers though.

I'm not sure about planting cuttings in mid winter. I should think they'd have to be placed in a propagator to root. Although in a conservatory they may be all right. Maybe someone else can help with that.
I never take cuttings in mid winter myself, even though I've got propagators, I think it's too cold and dark.

Thank you for this advice, Hywel. I will tidy up dead bits etc and let them be for now. They are really pretty and brighten up my day! I won't bother trying to take cuttings, so will throw out the few stems I have already cut without guilt!

I have been off line since Tuesday. I would have put the few stems in a glass of water say on a warm windowsill. When roots form pot them up and keep them slightly warm. I regularly took cuttings at school in Jan as that is when it cropped up on the syllabus. The labs never got below 10C.

March/April is good time to take them usually.

Oh! Thanks Eileen! I will rescue a couple of stems and try them. If not I can try with some of the others in March/April. Meanwhile I thought I'd leave the current flowers but remove any more buds that might appear over the winter.

I overwinter mine in my south facing porch, Pennyfarthing, and leave the flowers and buds on. They are a cheery sight! Needless to say, I remove dead and dying leaves and flowers and water very sparingly when the temperature isn't likely to drop below 0 C. Then in March / April I tidy them up and use the cuttings to make new plants. Some I keep to replace old plants that are no longer viable, the rest go to our horticultural society to raise funds at their Spring Bank Holiday sale in May. This year I am germinating seeds on my bedroom windowsill too, in the hope of getting a wider range of colour.
I guess your friend advising cutting them back for overwintering is aiming to produce stronger plants but here in the Chilterns I don't feel that is necessary.
If you are still in doubt why not cut back half and see if they do any better. I am tempted to do that myself next year, it may help with the overcrowding in the porch, lol