Woolly aphid

Getting rid of woolly aphids

Question from Wendy Green

My bougainvillea in my conservatory appears to be infested with wooLly aphids(I took a sample of white sticky masses to a local nursery who confirmed the diagnosis ( I haven't seen any actual insects) the infestation has spread to a number of Streptocarpus too. As I soon need to bring more plants from the garden in for winter protection I am anxious to eradicate it, Earlier I sprayed with Provado with little effect Last week I took most of the plants outside and cleaned off the white stuff as far as possible and sprayed again before bringing back in Any practical advice on what more if anything I can do would be most welcome I am on Essex UK coast and affected plants are all on north facing side of conservatory which is ventilated all summer with open door
Many thanks