Beginner Gardening: Help with my new rose garden please! , 3 by ChrisHawk

ChrisHawk wrote:
I dug in a border for a rose garden & purchased 10 new plants earlier in the year. They were doing fine until this past week (although some have failed to bud/flower). Now they all look as though they are dying. See photos. The only two in the patch that are okay are older ones transplanted from pots. There were a lot of aphids (greenfly) on the new plants. Have I killed them with too much insecticide? The plants were from a reputable seller and looked healthy on purchase.
Does anyone have any ideas please- and if I prune back hard now might that save them? I would be grateful for any advice!