I've never encountered this in 6 years of playing league

I was playing jungle today and... my team actively sabotaged me as much as they could. The support on leash purposefully stole both of my opening buffs. At first he apologized for blue and I let it slide, whatever mistakes happen. Then he leashes red for me to "make up" for it and steals that too and goes to lane. My mid laner played Tahm and would actively try to waste my ult (master yi) by swallowing me when I was about to get kills and spit me away or spit me into the enemy team on purpose. Even with that I was doing really well and had I not been actively sabotaged, i could have easily carried. It takes a lot to bother me. I've come to terms with league kind of having a lot of trolls and people that like to give up in the first 10 minutes, but this is beyond awful. They admitted at the end of the game they were a 4 man and just wanted to piss someone off. I didn't respond to anything they said after 5 minutes as I realized what was going on. What would you do in this situation @riot.
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