You only need one product, a fungicide only, not the combination products. I recommend Bayer Advanced Disease Control for Roses, Flowers, and Shrubs. Next, it takes time to stop an active breakout of blackspot. One application won't do it. The Bayer fungicide will halt and active breakout, but then the plant needs regular treatment to prevent additional blackspot. Leaves already affected will turn yellow, the products will not reverse the effects. If you keep on a regular treatment schedule, making sure to water the plants deeply prior to applying the fungicides, your blackspot issue should clear up in a month or so (it does take time).

The conbination Bayer products can take 6 or more weeks to become effective, in which time blackspot will take hold of the plants, that is one reason why I don't recommend their use. Applying the fungicide-only product (Disease Control) via spray application on a regular (10 - 14 day) schedule, should be enough to solve your issues.

Fungicides are like buying insurance you get it before something happens. That is true for fungicide use. As soon as the first leaves come out in the spring there should be a coating of fungicide on it. Then every two weeks, or what the label says for the product you use. Then you will have clean foliage all year.