Well I use Advantix (not to be confused with Advantage), on mine, it has worked fine and is administered like Frontline, it also has been effective on ticks.
I am sure some will recommend collars, which would be my next step such as Seresto collars they last longer too. I understand there is also a tablet which is now available.
I think the main thing is to also treat the area where your cocker sleeps and lies etc to prevent re-infestation and there are several sprays for this.
Forgot to say welcome i am sure as the day goes on more answers will appear.