I had a good look at the bush yesterday and found that there is a farm
on
it!!! I had a brainwave and looked at the underside of the leaves and
there
were all the aphids. I 've squirted water at them and got rid of the
ants,
but they came back later and i saw there were still loads of aphids. Time
consuming job isn't it? I could concentrate on the growing tips

This might sound a bit simplistic but gather up all the ladybirds and
larvae you can find and put them on the bushes. Encourage lacewings - their
larvea are even better at aphid eating than ladybirds. Try and keep the
ants down for a bit until the ladybirds can eat enough. I've had moderate
success like this.
Tim.