This for me falls under persistent infringement even if its done by ten different opponents. After a few/several fouls (when it becomes apparent it is a tactic), get the captain and tell him the next foul on the said player is a yellow card and then follow through.
Thoughts?
The only thing I would change is that I would not tell the captain that the next foul would engender a caution. It is still conceivable that they will have stopped fouling him for 75 minutes and then someone ends up carelessly fouling him and you're in a position where you now must caution him or go back on what you had said over an hour ago. Better to say "I can see that this is tactical. Enough is enough." and make some kind of public show with your arms to make it clear that enough is enough.