Something really needs to be done to shut down constant jungle invasions

I had a game where the enemy Lee Sin was constantly invading our Master Yi, often along with his Renekton top. By constantly, I mean he invaded 5 times before level 6, and died each time. I killed him once, Yi killed him twice, and our top killed him twice. He and Renekton killed Yi twice, making Lee 1-5-1, but Lee's kill was on the first invade, making his bounty relatively worthless.

However, our Yi wasn't ahead because Lee was usually managing to steal the camp he was at. We can't even blame Yi for failing to Smite, because the champion has no controlled burst, and Lee can easily steal with Q + Smite. The end result was that Yi and Lee were the same level and Yi had no real advantage, because he had no CS.

Meanwhile, my lane opponent quickly out-scaled me, because they were staying in lane while I responded to protect Yi. By the time they hit level 6, I was down almost two levels and over 30 CS. If I didn't respond, they wouldn't win the 2v2 with Renekton.

There is no winning option here. If I don't respond, Lee Sin and Renekton get insanely fed and Yi likely rage quits. If I do respond, my lane opponent pushes the wave and denies me huge amounts of CS and EXP.

This should not be a viable strategy, period. There needs to be some mechanic to protect jungles from constant invades like this.