I use rose clear, buy the concentrate for about 9 pound, makes like 30 litres. Mix it up in a hand pressure sprayer then off you toddle! It kills greenfly also provides protection because of the systemic action. It also deals with blackspot etc. If you have lots of roses, (I have maybe 20) it's the stuff to use. I too have noticed a dearth of ladybirds, also hoverflies are down. I plant between my roses with marigolds calendula etc, also scabious to try and attract as many natural predators. The problem is my garden is right next to 3 massive maples in the street, on a warm day you can literally see millions of greenfly coming off them. Spraying is not so great I know, I do spray in the evening, and check over the plants for any larvae or lady birds etc, so hopefully minimise 'friendly fire' casualties.
As I said, spraying isn't so great, but if you want your roses healthy and happy, it's what I do. I have tried spraying water at them to blast them off, but they are back in a day or two, also easy to damage new buds and shoots this way. The blackspot is the nightmare though, again rose clear at least slows it somewhat. Good luck.